IN  MEMORIAM 
George  Davidson 
1825-1911 

Professor  of  Geography 
University  of  California 


ELEMENTS  OF  GEOLOGY, 


FOR  THE 


USE  OF  SCHOOLS  AND  ACADEMIES. 


BY   PROF.    WM.    W.    MATHER,    GEOLOGIST. 


FOURTH  EDITION, 


NEW  YORK: 

CLEMENT  &  PACKARD, 

180  PEARL  STREET. 

And  sold  by  the  principal  Booksellers  in  the 

United  States. 

1841. 


/ '        €**  I 


Entered  according  to  Act  of  Congress,  in  the  year  one 
thousand  eight  hundred  and  thirty-eight,  by  WILLIAM  W. 
MATHER,  in  the  Clerk's  Office  of  the  District  Court  of  the 
United  States,  for  the  Southern  District  of  New  York. 


Stereotyped  by  Smith  &  Wright, 
216  William-st.,  New-York. 


rj 
PREFACE  TO  THE  FIRST  EDITION. 


THE  object  of  the  following  pages,  is,  to  exhibit  a  concise  sketch  of 
Geology  for  the  use  of  Academies  and  the  higher  classes  in  primary 
schools.  It  is  desirable  that  the  community  should  be  familiar  with 
the  leading  facts  of  this  science,  that  they  may  be  enabled  to  apply 
them  to  the  various  economical  purposes  of  life.  Every  science  is 
valuable  to  the  community,  in  proportion  as  the  knowledge  of  its 
facts  and  applications,  is  disseminated  among  the  mass  of  the  people. 
As  the  number  of  observers  increases,  more  facts  will  be  accumula- 
ted, and  the  resources  of  the  country  developed. 

Young  men  preparing  for  college  should  acquire  a  knowledge  of  the 
elementary  principles  of  geology  ;  and  in  their  collegiate  course,  the 
study  might  then  be  carried  much  farther  than  it  is  at  present.  Inde- 
pendent of  the  practical  utility  of  this  science,  it  furnishes  a  constant 
source  of  amusement,  or  pleasant  occupation,  in  journeying  over 
tracts  of  country  that  would  otherwise  be  perfectly  uninteresting.  It 
even  offers  an  inducement  for  the  exercise  of  walking  and  travelling 
to  those  who  would  otherwise  be  too  sedentary  in  their  habits. 

In  the  arrangement  of  the  subjects,  Bakewell's  Geology  has  been 
followed  with  few  exceptions.  The  works  employed  in  the  compila- 
tion of  this  work  were  Bakewell's  Geology,  edited  by  Professor  Siili- 
man  ;  Conybeare  &  Phillips'  Geology  ;  De  La  Beche's  Geology  ;  Ea- 
ton's Geological  Text  Book  ;  Cleaveland's  Geology ;  Greenough's 
Geology  ;  Silliman's  Journal ;  Journal  of  the  Academy  of  Nat.  Sciences 
of  Philadelphia ;  Annals  of  the  Lyceum  of  Nat.  History  of  New- 
York  ;  Maclure's  Geology  ;  American  Philosophical  Transactions  ; 
Philosophical  Transactions  of  the  Royal  Society  of  London  ;  Jour- 
nal of  the  Royal  Institution  of  Great  Britain,  and  Edinburgh 
Journal  of  Science.  When  quotations  are  made  without  refer- 
ence, they  are  from  the  American  edition  of  Bakewell's  Geology,  edi 
ted  by  Professor  Silliman,  and  containing  a  sketch  of  his  course  of 
Lectures  in  Yale  College.  The  author  has  introduced  some  things, 
for  which  he  alone  is  responsible,  and  derived  from  his  own  observa- 
tion. The  organic  contents  of  the  "  superior  rocks"  have  befin  but 
casually  touched  upon,  as  a  more  extended  course  is  required,  to  en- 
able one  to  distinguish  strata  by  their  organic  remains. 

This  little  work  is  a  sketch  of  the  author's  public  course  of  instruc- 
tion in  geology  ;  during  the  progress  of  which,  its  principles  are  illus- 
trated by  references  to  American  localities,  and  by  visiting  those  lo- 
calities when  practicable. 


PREFACE  TO  THE  SECOND  EDITION. 


Since  the  publication  of  the  first  edition  of  this  little  work,  a  multi- 
tude of  facts  has  been  collected  by  the  various  persons  engaged  in 
geological  investigations  in  Europe,  the  United  States,  and  other  parts 
of  the  world  ;  but  none,  it  is  believed,  tend  to  modify,  in  any  material 
degree,  the  elementary  principles  of  geology.  Some  new  theoretica* 
views  have  been  brought  forward  in  the  geological  reports  of  the 
several  States,  more  or  less  strongly  supported  by  facts,  and  many  new 
facts  have  been  observed  in  the  United  States  connected  with  econo- 
mical as  well  as  scientific  geology  ;  but  these  are  not  introduced,  as 
this  little  book  is  intended  only  to  give  a  sketch  of  the  elements  of 
geology,  and  a  few  facts  as  illustrations  of  the  principles  of  that 
science. 

Many  works  on  geology,  or  containing  geological  memoirs,  have 
been  used  in  the  compilation  of  this  work,  in  addition  to  those  men- 
tioned in  the  preface  to  the  first  Edition  ;  but  it  is  believed  that  credit 
has  been  given  to  the  authors,  by  reference  when  their  names  were 
known. 

For  the  last  six  years  the  author  has  been  occupied  during  a  large 
portion  of  the  time,  in  making  geological  explorations  in  the  employ- 
ment of  the  U.  S.,  of  several  of  the  States,  and  of  individuals. 

The  people  are  now  beginning  to  realize  the  economical  value  of  a 
knowledge  of  the  materials  that  form  the  surface  or  the  substrata  of 
their  lands,  as  is  evident  from  the  geological  surveys  that  are  now  in 
progress  in  more  than  one  half  the  States  of  the  Union.  These  sur- 
veys are  of  great  practical  utility  to  the  people  as  a  mass,  and  to 
many  individuals  in  particular.  But  if  a  knowledge  of  the  elementa- 

S  principles  of  geology,  and  of  the  more  common  and  useful  miner- 
s  and  rocks  were  diffused  in  the  community,  it  is  believed  that  many 
valuable  discoveries  would  be  made.  Every  man  would  know  what 
materials  were  accessible  on  his  land,  and  to  what  uses  they  could  be 
applied.  The  general  diffusion  of  this  kind  of  knowledge,  would  al- 
so tend  to  destroy  the  illusions  and  charlatanism  so  extensively  prac- 
tised in  this  country  by  the  designing,  and  by  the  Professors  of  the 
mineral  and  divining  rods.  It  is  not  intended  to  convey  the  idea  that 
all  who  use  the  mineral  rod  are  impostors  ;  but  that  those  who  are 
not  imposters  are  their  own  dupes. 

The  geologists  of  the  Several  States  cannot,  in  consequence  of  the 
great  areas,  to  be  examined,  and  the  limited  time  for  examinations,  do 
more  than  explore  particular  points,  and  unravel  the  general  geologi- 
cal structure  of  the  country.  The  developement  of  the  minute  local 
geology  of  each  farm,  must  depend  on  the  individuals  owning  the  pro- 
perty ;  and  with  the  hope  that  this  little  volume  may  aid  in  diffusing  a 
knowledge  so  useful  to  the  community,  it  is  now  sent  on  its  errand, 
end  may  God  grant  that  it  may  do  as  much  good  as  its  author  wishes. 


CONTENTS. 


INTRODUCTION. 

Geography  and  its  branches.  Physical  geography  in- 
eludes  geology.  Geology — definition  of.  Earth — of  what 
composed.  Objects  of  geology.  Minerals — definition  of. 
Geological  alphabet.  Veins — definition  of.  Associations  of 
minerals.  Rocks,  and  mineralogical  structure  of  rocks. 
Granular,  crystalline  and  compact  rocks.  Mean  density  of 
the  earth.  Indications  of  high  temperature  and  fluidity  of 
the  interior  of  the  earth — more  caloric  radiated  than  re- 
ceived — mean  temperature  not  changed  in  2,000  years. 
Tropical  animals  and  plants — remains  of  in  cold  climates. 
Supposed  change  of  the  earth's  axis.  Impossibility  demon- 
strated— rapidity  of  undulations  during  earthquakes — occa- 
sional simultaneous  action  of  valcanos — increase  of  tern, 
perature  on  descending  into  the  earth.  Explanation  of  the 
interior  high  temperature  of  the  earth  offered  by  an  Ameri- 
can writer.  Crust  of  the  globe  only  exposed  to  observation. 
Relative  thickness  actually  exposed  to  observation.  .  .13 

CHAPTER  I. 

• 

Foundation  of  geology  laid  by  Lehman,  Primitive  and 
secondary  rocks.  Organic  remains,  fossils,  and  petrifactions. 
Ocean  has  not  always  been  confined  to  its  present  limits. 
Evidences  of  this.  Conclusions  from  these  facts.  Eleva- 
tion of  continents,  and  evidences.  Disruption,  contortion, 
overturned  and  highly  inclined  strata.  Ancient  beaches, 

i* 


VI  CONTENTS. 

valleys  of  excavation,  and  evidences  of  denuding  causes. 
Remains  of  animals  and  plants  imbedded  in  rocks— how  en. 
tombed  there — different  from  existing  species.  Strata  depo- 
sited in  succession.  Period  of  time  to  produce  the  fossilif- 
erous  rocks.  Explanation  of  the  term  day.  Interpretation. 
Bakewell's  views.  Geological  discoveries  consistent  with 
the  Bible.  Extracts  from  Buckland's  Geology — Mantell's— - 
Chalmer's  Evidences  of  the  Christian  Revelation — Sedg- 
wick's  discourse. 25 


CHAPTER  II. 

Elementary  bodies  forming  the  mass  of  the  globe.  Prin- 
cipal elementary  bodies  and  relative  proportions.  Slight 
discussion  of  these  and  their  compounds.  Oxygen,  chlo. 
rine,  quantity  of  salt,  and  mean  depth  of  the  ocean.  Hy- 
drogen, and  its  uses — silicon,  sand,  glass,  carbon,  charcoal, 
mineral  coal,  and  diamond — sulphur  and  its  compounds—- 
iron and  its  combinations — oxides,  earths,  and  alkaline 
earths — minerals  formed  of  the  above  substances — 45  other 
simple  bodies  known — slight  description  of  each.  .  .  48 

CHAPTER  III. 

Geological  alphabet,  viz.  quartz,  properties,  crystals, 
quantities,  feldspar,  constituent  of  rocks,  mica,  and  uses, 
hornblende,  augite,  chlorite,  talc,  gypsum,  limestone,  serpen. 
tine,  slate  and  clay 62 

CHAPTER  IV. 

ON   STRATIFICATION. 

Rocks  regularly  arranged.  Practical  utility  of  a  know, 
ledge  of  this  arrangement.  Dip  of  strata.  Utility  of  the 
dip  to  man.  Uniformity  of  scenery  along  the  line  of  bear, 
ing.  Change  of  scenery  along  the  line  of  dip.  Importance 
of  determining  the  order  of  superposition.  Practical  dim". 
culties.  Not  generally  necessary  to  bore  to  determine  the 


CONTENTS.  Vii 

order  of  superposition.  Bearing  is  known  by  ascertaining 
the  dip.  Outcrop  of  strata.  Thickness  of  strata — how  es. 
timated.  Conformable  and  uncomformable  strata.  Strati, 
ficattun  of  slate  and  slaty  layers.  Difficulty  in  determining 
the  strata  planes  of  slate  rocks — how  obviated.  Clays  also 
divided  .by  parallel  seams  dependent  on  some  law  of  nature. 
Thickness  of  strata.  Bent  and  contorted  strata.  Liability 
to  mistake  the  dip  and  position  of  strata.  Dip — how  deter 
mined.  Sources  of  error  in  determining  the  superposition. 
Seams  sometimes  mistaken  for  strata  planes.  Anticlinal 
axis,  (d.)  Strata  intersected  by  valleys.  Faults  and  dykes, 
and  sources  of  error 72 

CHAPTER  V. 

FORMATIONS   AND   PRIMITIVE    ROCKS. 

Definitions  of  formations.  Independent  formations.  Geo- 
logical equivalents,  and  parallel  formations.  Some  rocks 
not  stratified.  Rocks  traversed  by  veins.  Metallic  ores 
found  mostly  in  veins.  Origin  of  veins.  Walls,  floor,  and 
roof  of  veins.  Systems  of  veins.  Ages  of  veins — how  de- 
termined. Grouping  of  rocks  into  primitive,  secondary,  &c. 
Tertiary,  diluvion,  alluvion,  &c.  Substitution  of  other 
names.  Conybeare  and  Phillips's  arrangement.  De  La 
Beche's  classification.  Primary  or  primitive  rocks.  Granite 
— porphyritic — stratification  of  other  rocks  near — division 
seams  of.  Eurite.  Graphic  granite.  Oxide  of  tin  in  gra- 
nite. Granite  as  a  building  material.  Gneiss  and  mica 
slate.  Stratification,  and  slaty  structure  of  gneiss.  Pas- 
sage of  gneiss  and  mica  slate  into  each  other.  Talcose  and 
chloritic  slate.  Hornblende  rock,  gneissoid  hornblende. — 
Augite  rocks,  and  trap  rocks.  Serpentine  rocks,  and  verd 
antique.  Crystalline  limestone.  Marbles.  Great  extent 
of  this  rock  in  the  United  States.  Quartz  rock.  .  ".  84 


Vlil  CONTENTS. 

CHAPTER  VI. 

TRANSITION    ROCKS. 

Situation  of  transition  rocks.  Organic  remains  are  an- 
cient  records.  Ores  in  transition  rocks.  Line  of  demarka- 
tion  between  primitive  and  transition  rocks.  Slate  the 
lowest  of  transition  rocks.  Names  of  the  principal  transi- 
tion rocks.  Synonims  and  varieties  of  slate.  Graywacke 
and  graywacke  slate.  Red  sandstone,  new  and  old.  Red 
sandstone  of  Connecticut  and  New  Jersey,  and  its  extent. 
Fossil  remains  and  ores  found  in  this  stone.  Transition  or 
mountain  limestone.  Organic  remains  found  in  it.  Encri- 
nites.  Lead  ore  in  this  mountain  limestone.  Caverns  in 
mountain  limestone,  and  sink  holes.  Rivers  engulphed. 
Large  springs.  Hornstone  and  chert.  .  .  .97 

CHAPTER  VII. 

SECONDARY   ROCKS. 

Secondary  rocks  divided  into  upper  and  lower  secondary. 
Coal  and  salt  formations  most  important.  Coal  measures, 
and  description  of  the  members — coal,  sandstone,  shale,  iron 
ore,  and  limestone  of.  Distinction  between  the  transition 
and  lower  secondary  drawn  from  the  fossil  remains.  Plants 
of  coal  formation  analogous  to  those  of  the  tropics.  De- 
duction from  an  extensive  series  of  these  facts.  Coal  mea. 
sures  frequently  not  conformable  to  lower  strata.  Coal 
formation  somewhat  variable  in  position.  Some  coal  rocks 
indicate  a  mechanical  origin — others  a  chemical.  Derange- 
ments of  the  strata.  Some  strata  rapidly  deposited.  Many 
strata  of  coal  in  one  deposite.  Coal  fields,  origin  and  shape. 
Alternations  of  strata.  Origin  of  coal.  Fossil  remains  of 
plants  in  shale.  Outcrop  of  coal  beds.  Methods  of  search, 
ing  for  coal.  Coal  of  the  United  States  and  Europe.  Va- 
rieties of  coal.  Geological  position  of  bituminous  coal  and 
anthracite.  Wood  coal,  lignite,  jet.  Amber  with  imbedded 
insects 104 


CONTENTS.  IX 

CHAPTER  VIII. 

UPPER   SECONDARY   ROCKS. 

Division  of  the  upper  secondary  rocks.  Synonims,  and 
important  minerals  of  the  red  sandstone.  Magnesian  lime- 
stone.  Effect  of  magnesia  on  soils.  Distinction  between 
the  sandstone  of  the  coal  measures,  and  of  the  red  sandstone. 
Organic  remains  of  the  red  sandstone.  Saurians.  Minerals 
of  red  sandstone.  Rock  salt.  Gypsum.  Saltmines  of  Europe 
and  America.  Deposition  of  salt  in  Africa.  Salt  springs. 
Salt  licks  of  the  United  States.  Fossil  bones  at  the  licks — 
Mastodon  and  Elephant.  Origin  of  salt  deposits  and  salt 
springs.  Distribution  of  salt.  Lias  limestone  and  clay. 
Lithographic  stone,  and  its  necessary  qualities.  Saurians 
of  great  magnitude  in  lias.  Lias  clay  used  to  make  hydrau- 
lic cement.  Lias  clay  used  to  make  alum.  Oolite  and  or- 
ganic remains  of  oolite.  Oolitic  limestone  in  the  United 
States.  Organic  remains  and  uses  of  oolite.  Coral  ragg. 
Wealdon  rocks.  Gigantic  saurian  animals.  Chalk  forma- 
tion. Flint.  Chalk  formation  of  the  United  States.  114 

CHAPTER  IX. 

TERTIARY   ROCKS. 

Tertiary  rocks  described.  Minerals  of  the  tertiary.  Ter- 
tiary often  confounded  with  alluvial  and  diluvial.  Stratifi- 
cation of  the  tertiary.  Fossils  of  the  tertiary.  Mammifers 
of  the  tertiary  and  insecta.  Testacea.  Basins  of  Paris  and 
London.  Artesian  wells.  Fossil  fishes  of  Europe  and  the 
United  States 128 

CHAPTER  X. 

DILUVIAL   DEPOSITS. 

Distinction  between  alluvial  and  diluvial  deposits.  Dis. 
cription  of  diluvion.  Erratic  blocks.  Explanation  of  the 
transport  of  those  blocks.  Theories  explanatory  of  the 


X  CONTENTS. 

same.  Bore  or  Pororoca.  Examples  of  the  effects  of  the 
tide.  Examples  of  the  effects  of  the  waves.  Examples  of 
the  effects  of  the  lakes  bursting  their  boundaries.  Minerals 
and  ores  of  the  diluvial  deposits.  Metals  of  the  diluvial  de- 
posits. Bone  caves.  Bone  breccias.  Bone  breccias  con- 
taining also  land  and  fresh  water  shells.  Bones  of  various 
animals  in  caves.  Human  bones  in  diluvial  gravel,  Human 
bones  in  recent  rocks. 136 

CHAPTER  XI. 

ALLUVIAL    DEPOSITS. 

Description  of  alluvial  deposits.  Animal  and  vegetable 
remains  imbedded.  Causes  of  alluvial  action.  Fall  of  the 
Dent  du  Midi.  Landslip  of  Champlain.  Glaciers,  and  their 
uses.  Transport  of  rocks  by  ice.  Delta  of  the  Po.  Rivers 
raise  their  beds  in  some  parts  of  their  course,  arid  excavate 
in  others.  Dykes  on  the  Mississippi.  Transport  by  tides 
and  oceanic  currents.  Illustration  of  the  power  of  water 
in  transporting  rocks.  Effects  of  wind  in  transporting  ma- 
terials. Encroachments  of  sands  on  cultivated  lands.  Sands 
of  Egypt.  Petrified  forest.  Shoals  from  drifted  sands.  Coral 
reefs  of  Pacific  and  Indian  Ocean.  Silicious  and  calcareous 
deposits  from  springs.  Peaty  alluvions  and  description  of.  149 

CHAPTER  XII. 

TRAP   ROCKS. 

Trap  and  volcanic  rocks  have  no  regular  geological  posi- 
tion. Composition  of  trap  rocks.  Trap  rocks  occur  in  dykes, 
beds,  columnar  and  globular  masses.  Derivation  of  the  term 
trap.  Greenstone — composition  and  discription  of.  Exam- 
ples of  trap  in  the  United  States.  Greenstone.  Sienitic. — 
Clinkstone.  Wacke.  Amygdaloid.  Basalt.  Dykes.  Faults. 
Natural  walls  of  North  Carolina.  Effects  of  balsatic  dykes 
on  the  rocks  traversed.  Experiments  on  trap  and  limestone. 
Globular  and  columnar  form  of  basalt.  Organic  remains  in 
basalt.  .  .  162 


CONTENTS.  XI 

CHAPTER  XIII. 

EARTHQUAKES,  VOLCANIC  PHENOMENA,  AND  VOLCANIC  ROCKS. 

Earthquakes  and  volcanic  phenomena  frequently  accom- 
pany eaeh  other.  Phenomena  attending  and  preceding  earth- 
quakes. Extent  of  the  effects.  Elevation  of  Jorullo.  Cause 
of  earthquakes.  Explosion  of  coal  mines.  Safety  lamp. 
Heaving  of  the  ground  during  earthquakes.  Volcanos,  defi- 
nition of.  Crater.  Materials  ejected.  Moya.  Mud.  Fishes. 
Lava.  Gases.  Hot  springs.  Indication  of  a  volcanic  erup- 
tion. Time  of  eruptions  and  quantities  of  erupted  matter. 
Eruptions  of  .^Etna.  Eruptions  of  Skapta  Jokul,  in  1783. 
Eruptions  of  Sumbawa.  Eruptions  of  Vesuvius.  Columnar 
lava  of  Vesuvius.  Long  repose  of  volcanos,  and  examples. 
Submarine  volcanos.  Volcanic  islands  rise  from  the  sea,  and 
some  sink  again.  Volcanos  in  groups.  Volcanic  mountain 
engulphed.  Composition  of  volcanic  rocks.  Sulphur.  Pum- 
ice. Trachyte.  Lava,  &c 172 

CHAPTER  XIV. 

RECAPITULATION    OF  THE  PRINCIPAL   FACTS   OF  GEOLOGY. 

j  Slight  discussion  of  some  theories.  Geology  has  no  ne- 
cessary connection  with  theory.  Uses  of  theories.  Werne- 
rian  and  Huttonian  theories  excited  much  discussion.  Nei- 
ther of  them  fully  sustained  by  facts.  Wernerian  theory. 
Huttonian  theory.  Remarks  upon  these  theories.  Professor 
Silliman's  views  on  this  subject.  ....  194 

USEFUL  APPLICATIONS  OF  GEOLOGY. 

I.  AGRICULTURE. 

Soil  dependent  on  composition  and  substratum.  Light 
and  heavy  soils.  Soils,  how  formed.  Soils  of  different  geo- 
logical formations.  Variations  in  productiveness  of  soils. 
Texture  of  soils,  discussion  of.  Composition  of  soils,  dis- 
cussion of,  Effect  of  iron  on  vegetation.  Permanency  of 


Xll  CONTENTS. 

soils.  Effects  of  springs  and  substrata.  Effects  of  tilling 
land  and  washing.  Alluvions  of  Hudson.  Food  of  plants. 
Connection  of  geology  and  agriculture.  Effect  of  imper- 
vious and  pervious  rocks  on  the  soil.  Effect  of  loose  stones 
in  the  soil.  Drainage  by  means  of  pervious  strata.  Drain, 
age  by  means  of  faults.  Mixtures  of  mineral  substances  to 
improve  soils.  Importance  of  lime  in  soils.  Importance 
of  particular  substances  in  soils  for  particular  kinds  of 
tillage 213 

II.   ROADS, 

Materials  for  construction.    Location  in  regard  to  strati, 
fied  rocks 230 

III.   CANALS. — 236. 

rv.  WELLS. — 236. 

V.    MINING. 

Geological  knowledge  necessary  to  the  preliminary  ex* 
plorations,  and  to  the  working  of  mines.         .        .        238 

VI.    BUILDINGS. 

Importance  of  a  judicious  selection  of  materials.        240 

SKETCH  OF  THE  HISTORY  OF  GEOLOGIC 

Concluding  remarks.      ••••••    244 


INTRODUCTION. 


GEOGRAPHY  is  a  description  of  the  Earth,  or  it 
is  a  science  that  teaches  the  positions  of  all  the  re- 
gions  of  the  earth,  with  regard  to  each  other,  and 
describes  the  principal  objects  they  contain.  Many 
of  the  sciences  group  themselves  around  Geography, 
and  yield  to  it,  and  to  each  other,  a  mutual  support. 

Geography  is  now  considered  in  a  more  enlarged 
sense  than  it  was  originally.  It  now  comprehends 
four  great  divisions,  viz  : 

1.  Mathematical   geography  occupies   itself  in 
measurements  of  the  earth's  surface,  and  in  ascer- 
taining the  location  of  places,  with  reference  to  cer- 
tain fixed  lines,  or  lines  of  latitude  and  longitude. 

2.  Historical  geography  consists  in  noting  the 
times  of  particular  events,  and  the  places  and  cir- 
cumstances of  their  occurrence. 

3.  Political  geography  describes  the  earth  in  its 
relations  with  men. 


QUESTIONS  ON  THE  INTRODUCTION  TO  GEOLOGY. 

What  is  geography  ?    What  does  geography  now  compre- 
hend ?    What  is  mathematical  geography  ?     What  is  histo- 
rical  geography  ?    What  is  political  geography  ? 
2 


14  INTRODUCTION. 

4.  Physical  geography  is  a  branch  of  geography 
which  is  freed  from  the  limitation  of  kingdoms  and 
empires,  and  all  artificial  divisions.  It  embraces 
the  natural  history  of  the  earth, — all  objects  that 
can  be  represented  by  geographical  maps,  and  every 
thing,  depending  on  causes,  which  may  have  con- 
curred,  at  different  times,  in  the  actual  constitution 
of  the  earth.  Physical  geography  includes  GEO- 
LOGY. 

GEOLOGY  is  a  science  that  has  for  its  object  the 
examination  of  the  structure  of  the  earth,  the  man- 
ner  in  which  all  the  materials  forming  it  are  ar- 
ranged with  regard  to  each  other,  and  the  action 
of  frosts,  rains,  floods,  tides,  winds,  earthquakes  and 
volcanoes,  in  effecting  changes  upon  its  surface. 
The  study  of  geology  leads  us  to  examine  and  re- 
flect upon  the  works  of  nature  that  we  see  every 
where  scattered  around  us.  It  reveals  to  us  the  his- 
tory of  the  great  convulsions  and  revolutions  that 
the  earth  has  experienced  at  remote  periods  of  time. 
The  question,  "  to  the  scholar"  says  the  Reviewer  of 
Silliman's  Chemistry  in  the  Christian  Spectator, 
vol.  ii.  p.  135,  "  personally  the  relations  of  a  particu- 
lar branch  of  knowledge  to  the  economical  pur- 
poses of  life,  is  of  secondary  importance.  There- 
fore he  enquires,  not  whether  a  science  will  furnish 
pecuniary  profit  or  promote  bodily  comfort  and  en- 
joyment, but  rather  if  its  investigations  lead  to  phy- 
sical and  moral  truth;  whether  the  objects  with 


What  is  physical  geography  ?  or  what  does  it  embrace  ? 
What  is  geology?  What  does  geology  lead  us  to  examine? 
What  does  it  reveal  to  us  ?  What  should  the  scholar  enquire  ? 


INTRODUCTION.  15 

which  it  is  conversant,  are  of  sufficient  interest  to 
excite  curiosity  and  bring  into  exercise  the  higher 
powers  of  the  mind." 

"  What  is  the  earth  made  of?" 

has  probably  presented  itself  to  every  mind,  and  this 
question,  under  certain  limitations,  includes  most  of 
the  objects  of  geology,  viz  : 

"  What  are  the  substances  of  which  the  earth  is 
composed  ? 

What  is  the  order  in  which  they  are  arranged  ? 

What  are  the  changes  which  they  appear  to  have 
undergone  ?" 

"  The  true  object  of  Geology  is  to  describe  the 
earth  as  it  is  at  present,  so  far  as  it  is  exposed  to  our 
observation ;  and  thus  far,  this  science  is  susceptible 
of  as  much  certainty  as  any  of  the  physical  sciences." 
[Humboldt  on  rocks.] 

Geology  being  a  science  that  has  for  its  object  a 
knowledge  of  the  earth's  structure,  as  far  as  it  lies 
open  to  our  observation,  the  fundamental  point  on 
which  it  rests,  is,  to  ascertain  the  order  in  which 
the  materials  constituting  its  surface  are  super- 
posed on  each  other.  It  is  necessary  to  say  its 
surface,  far  below  this,  comparatively,  we  cannot 
penetrate. 

If  at  any  point  of  the  earth's  surface  we  examine 
the  substances  composing  it,  we  find  that  they'are 
either  clay,  sand,  gravel,  rock,  or  various  mixtures 


What  are  the  principal  subjects  of  geological  enquiry? 
What  is  the  true  object  of  geology?  What  is  it  designed  to 
ascertain?  Of  what  materials  do  we  find  the  earth  com- 
posed  ? 


16  INTRODUCTION. 

of  these,  and  that  if  rock  be  not  found  at  the  sur- 
face, it  may  be  by  digging  to  some  depth  below,  and 
that  below  this,  the  solid  rock  continues  as  far  as  the 
power  of  man  has  hitherto  enabled  him  to  penetrate. 
When  we  slightly  examine  the  surface  of  the 
earth,  every  thing  seems  without  regularity  ;  but 
by  close  observation,  we  see  that  the  rocky,  as  well 
as  the  earthy  materials  exposed  to  our  view,  are  not 
all  alike,  but  differ  much  in  their  appearance,  pro- 
perties and  composition,  and  that  these  rocks  are 
arranged  in  a  regular  order  one  over  the  other. 
The  rocks  and  other  earthy  bodies  are  composed  of 
minerals.  Sometimes  a  single  kind  of  mineral 
forms  the  masses  of  sand,  clay  or  rock  ;  but  more 
often,  two  or  more  mineral  substances  are  aggre- 
gated to  form  those  bodies. 

Minerals,  are  those  bodies  found  in  or  upon  the 
earth,  that  are  not  animal  or  vegetable  productions. 
There  are  only  ten  that  occur  in  such  abundance 
as  to  form  the  proper  constituent  parts  of  the  rocks, 
and  these  are  by  Professor  Eaton  called  the  geolo- 
gical alphabet. 
They  are 

QUARTZ  ;  CHLORITE  ; 

FELDSPAR  ;  TALC  ; 

MICA  ;  GYPSUM  ; 

HORNBLENDE  ;  LIMESTONE  ; 

AUGITE  ;  SERPENTINE. 


Does  the  solid  rock  always  occur  within  a  moderate  depth 
from  the  surface  ?  and  how  far  does  it  continue  ?  Of  what 
are  the  rocks  composed  ?  What  are  minerals  ?  How  many 
and  what  minerals  form  the  rocks  ?  Where  do  the  other  mi 
nerals  occur? 


INTRODUCTION.  17 

The  other  minerals  are  found  in  veins,  which  ap- 
pear to  have  been  once  open  fissures  in  the  rock, 
and  since  filled  with  mineral  matter ;  or  in  beds 
which  are  isolated  masses  of  mineral,  imbedded  in 
other  rocks  ;  or  else  they  are  disseminated,  or  scat- 
tered irregularly  in  the  rocks  in  small  grains  and 
masses. 

Certain  mineral  substances  are  found  almost  con- 
stantly associated  with  certain  others,  so  that  if  one 
be  found  in  any  particular  situation,  the  others  may 
be  expected  to  be  found  by  searching  for  them. 
Salt,  and  salt  water,  for  instance,  are  almost  always 
found  in  connection  with  clay  and  gypsum.  Lead 
ores  with  those  of  zinc.  Tin  ores  with  those  of  tung- 
sten and  with  topaz.  This  fact  is  observed  not 
only  among  the  ores  and  the  common  minerals  and 
gems,  but  those  minerals  which  by  their  aggrega- 
tion constitute  rocks,  form  masses  so  very  similar 
that  specimens  from  far  distant  countries  can 
scarcely  be  distinguished  from  each  other  eves  by 
a  practised  eye. 

Rocks  are  the  aggregates  of  grains  or  pieces  of 
one  or  more  minerals,  adhering  to  each  other  so  as 
to  form  masses. 

The  grains  of  minerals  are  so  small  in  some  rocks, 
as  not  to  be  distinguished  from  each  other,  and  then 
these  rocks  are  said  to  be  compact.  When  the 

What  are  veins  ?  and  what  beds  ?  When  are  minerals  dis- 
seminated ?  Do  particular  minerals  almost  constantly  accom- 
pany each  other  ?  What  minerals  accompany  salt  and  salt 
water  ?  What  ores  are  associated  with  the  lead  ores  ?  What 
ores  and  mineral  with  tin  ores  ?  What  of  those  minerals  that 
constitute  rocks  ?  What  are  rocks  ?  When  are  they  compact  ? 
2* 


18  INTRODUCTION. 

grains  are  distinguishable  from  their  magnitude, 
the  rock  is  said  to  be  granular  in  its  structure. 
When  the  parts  composing  the  rocks  show  plane 
and  brilliant  surfaces  on  being  broken,  they  are  said 
to  be  crystalline.  The  close  grained  limestones  are 
generally  instances  of  the  compact  structure.  Com- 
mon  sandstone  shows  the  granular.  The  white 
marbles  and  granite,  the  crystalline  structure. 
Rocks  are  said  to  be  slaty,  or  to  have  a  slaty  struc- 
ture, when  they  split  out  in  thin  layers  like  common 
slate,  or  roofing,  or  drawing  slate. 

The  mean  density*  of  the  earth  is  about  five  times 
greater  than  water.  And  as  the  mean  density  or 
specific  gravity  of  the  mass  of  materials  at,  and 
near  the  surface  of  the  earth  is  only  two  and  a 
half,  it  follows,  that  the  mean  density  at  some  dis- 
tance below,  is  greater  than  at,  and  near  its  surface. 

There  are  certain  phenomena,  which  seem  to  in- 
dicate, that  the  mass  of  the  earth  at  some  distance 
below  the  surface,  must  be  in  a  liquid  or  melted 
state. 

1.  The  earth  has  the  exact  form  that  a  fluid  body 
would  assume,  moving  as  the  earth  does. 


When  granular  ?  and  when  crystalline  ?  What  rocks  are 
instances  of  the  compact,  granular,  and  crystalline  struc- 
tures ?  What  is  the  slaty  structure  ?  What  is  the  mean  den- 
sity  of  the  earth  ?  What  is  the  mean  density  of  the  bodies 
near  the  surface  ,,of  the  earth  ?  What  results  from  this  diffe. 
rence  ?  What  form  has  the  earth  ? 


*  The  density  and  specific  gravity  are  synonymous,  and  both  mean 
the  relative  weight  of  a  body,  when  compared  with  an  equal  bulk  of 
water. 


INTRODUCTION.  19 

2.  The  earth  loses  more  caloric*  than  it  receives 
in  the  course  of  a  year,  and  sufficient  to  melt  seve- 
ral feet  in  depth  of  snow  over  its  whole  surface. 
This  would  indicate,  that  it  is  a  gradually  cooling 
mass.  "  The  mean  temperature  of  the  earth  has  not 
varied  for  the  last  2000  years,  as  the  length  of  the 
day  is  the  same  now  as  then.  A  change  of  the  mean 
temperature  would  cause  a  change  of  the  velocity 
of  rotation,  and  consequently  of  the  length  of  the  day. 

The  occurrence  of  animals  and  plants  imhedded 
in  such  vast  numbers  in  the  rocks  in  high  lati- 
tudes, whose  analogues  are  found  only  in  tropical 
climates,  seem  to  indicate  that  the  mean  tempera- 
ture of  the  globe  has  been  at  some  former  period 
much  superior  to  what  it  is  at  present.  It  has  been 
attempted  to  account  for  these  tropical  fossils  oc- 
curring in  high  latitudes,  by  supposing  that  the  axis 
of  the  earth  formerly  had  a  different  position  from 
the  present  one,  and  that  the  polar  regions  had  once 
been  where  the  equator  is  now,  but  astronomical 
observations  show  that  this  cannot  have  been  the 
case. 

"  The  most  conclusive  argument  against  the  fact 
of  any  disturbance  having  in  remote  antiquity, 


What  indicates  that  the  earth  is  a  gradually  cooling  mass  ? 
How  long  has  the  temperature  of  the  earth  not  varied? 
What  would  a  change  of  temperature  cause  ?  Where  are 
animals  and-  plants  imbedded?  What  do  they  indicate? 
How  is  it  accounted  for  ? 


t  Caloric  is  that  which  enters  into  a  body  when  heating,  and  passes 
off  when  cooling.  Heat  is  a  term  applied  to  the  sensation  we  per- 
ceive in  touching  a  hot  body. 


20  INTRODUCTION. 

taken  place  in  the  axis  of  the  earth's  rotation  is  to 
be  found  in  the  lunar  irregularities,  which  depend 
on  the  earth's  spheroidal  figure."  However  insuffi- 
cient the  mere  transfer  of  the  mass  of  the  ocean, 
from  the  old  to  the  new  equator,  might  be  to  insure 
the  permanence  of  the  new  axis,  the  enormous  abra- 
sion of  the  solid  materials  of  such  immensely  pro- 
tuberant continents  as  would  on  that  supposition 
be  left  by  the  violent  and  constant  fluctuation  of  an 
unequilibrated  ocean,  would  according  to  an  ingeni- 
ous remark  of  Prof.  Playfair,  no  doubt  in  lapse  of 
some  ages  remodel  the  surface  to  the  spheroidal 
form  ;  but  the  lunar  theory  teaches  us  that  the  inter- 
nal strata  as  well  as  the  external  outline  of  the  globe 
are  elliptical,  their  centres  being  coincident  and 
their  axes  identical  with  those  of  the  surface, — a 
state  of  things  incompatible  with  a  subsequent  ac- 
commodation of  the  surface  to  a  new  and  different 
state  of  rotation  from  that  which  determined  the 
original  distribution  of  the  component  matter." 
[Rep.  Brit.  Assoc.  i.  p.  407.] 

The  Baron  Fourrier  has  computed  that  the  ex- 
cess of  radiant  heat  of  the  earth,  over  that  absorbed 
by  the  sun,  does  not  cause  a  difference  in  mean 
temperature,  of  ^  of  a  degree  of  the  centigrade  ther- 
mometer, and  the  cooling  of  the  earth  may  now  be 
considered  as  having  reached  an  asymptotic  condi- 
tion. [Rep.  Brit.  Assoc.  i.  p.  221.] 

3.  The  rapidity  with  which  motion  is  communi- 
cated over  extensive  portions  of  the  earth  during 


What  is  said  of  the  axis  of  the  earth's  rotation?  What 
does  the  lunar  theory  teach  us  ?  What  is  said  of  the  radiant 
heat  of  the  earth '( 


INTRODUCTION.  21 

earthquakes,  is  somewhat  like  the  ground  swell,  felt 
on  the  ocean,  and  on  floating  icefields,  hours  before 
any  motion  of  the  air  is  perceived. 

4.  The  occasional  simultaneous  action  of  vol- 
canos,  far  distant  from  each  other. 

5.  After  going  50  or  60  feet  below  the  surface  of 
the  earth,  the  heat  increases  according  to  the  depth, 
from  one  to  two  degrees  of  Farenheit's  thermometer 
for  every  100  feet.     The  warmth  of  the  earth  below 
the  surface  is  variable  from  30  to  60  feet,  in  conse- 
quence of  the  variation  of  the  seasons,  and  the  filter- 
ing of  rain  and  spring  water  through  the  ground  ; 
but  below  that,  the  temperature  is  uniform  from 
season  to  season,  and  warmer  as  you  descend  far- 
ther.    In  the  caves  under  the  city  of  Paris,  the 
thermometer  does  not  show  a  variation  of  one-tenth 
of  a  degree  of  Farenheit's  thermometer  from  one 
year's  end  to  another. 

If  the  temperature  increases  with  the  same  rapi- 
dity to  the  centre  of  the  earth,  as  it  does  for  2000 
feet  from  the  surface,  the  heat,  from  30  to  60  miles 
below,  would  be  sufficient  to  melt  the  most  refrac- 
tory rocks. 

An  explanation  of  the  temperature  of  the  interior 
of  the  earth,  is  offered  by  a  writer  in  the  American 


What  resembles  the  ground  swell  ?  How  far  below  the 
surface  is  the  temperature  variable  from  the  effects  of  the 
seasons,  springs  &c.  ?  Below  that  depth  does  the  tempera, 
ture  vary  at  any  particular  place  ?  As  you  descend  deeper 
does  the  temperature  diminish  or  increase  ?  What  do  the 
foregoing  phenomena  seem  to  indicate  ?  Should  the  temper- 
ature increase  at  the  rate  observed,  at  what  depth  would  the 
heat  be  sufficient  to  melt  the  rocks  ? 


22  INTRODUCTION. 

Quarterly  Review,  vol.  xvi.  p.  433.  He  remarks, 
"  If  solids  were  capable  of  indefinite  compression, 
steel  would  be  compressed  into  ^,  and  stone  into  -i 
of  its  bulk  at  the  centre  of  the  earth ;  but  long  be- 
fore such  a  degree  of  condensation  could  be  marked, 
the  temperature  would  be  so  far  increased  as  to 
cause  the  bodies  to  enter  into  igneous  fusion ;  and 
it  has  been  calculated,  that  at  the  depth  of  30  miles, 
every  solid  substance  known  to  exist  at  the  earth's 
surface,  would  be  melted  by  the  heat  caused  by  the 
pressure  of  the  superincumbent  mass." 

It  is  only  the  crust  of  the  globe  that  comes  under 
our  direct  observation,  and  it  is  to  this,  that  geology 
more  particularly  confines  itself. 

In  speaking  of  the  crust  of  the  globe,  it  is  not 
meant  to  convey  an  idea  that  the  earth  is  hollow,  or 
in  a  fluid  state,  but  that  the  part  coming  under  our 
observation  is  analogous  to  a  thin  crust  or  rind,  in 
comparison  with  the  mass  of  the  earth.  The  greatest 
depth  to  which  man  has  penetrated  is  less  than  3000 
feet,  and  the  highest  mountains,  the  Himalaya,  are 
less  than  27,000,  so  that  not  more  than  30,000  feet 
from  the  surface  towards  the  centre,  is  exposed  to 
our  observation.  30,000  feet  is  about  one-seven 
hundredth  part  of  the  distance  from  the  surface  to 
the  centre. 


If  solids  were  capable  of  compression  what  would  that  of 
steel  be  ?  Of  stone  ?  What  would  be  the  result  of  such  com- 
pression ?  What  part  of  the  Earth  comes  under  our  obser- 
vation? What  is  meant  in  speaking  of  the  crust  of  the 
globe  ?  To  what  depth  has  man  penetrated  into  the  Earth  ? 
How  high  are  the  highest  mountains  on  the  globe  ? 


INTRODUCTION.  23 

This  portion  of  the  earth  exposed  to  our  observa- 
tion, bears  no  more  proportion  to  the  magnitude  of 
the  globe,  than  does  the  thin  coat  of  varnish  on  an 
artificial  globe  to  its  mass.  The  most  elevated 
mountains,  may  be  compared  to  the  dust  collected 
on  a  school  globe ;  and  the  great  mountain  chains, 
to  fibres  of  silk  stretched  across  its  surface. 

Such  views  show  the  insignificance  of  man  when 
compared  with  the  stupendous  works  of  our  Creator , 
and  we  may  well  exclaim  with  the  Psalmist :  "  What 
is  man  that  thou  art  mindful  of  him." — Ps.  viii.  4. 


How  does  the  whole  thickness  that  we  can  examine,  com- 
pare with  the  whole  Earth  ?  To  what  may  the  mountains 
and  mountain  chains  be  compared  ? 


ELEMENTS    OF    GEOLOGY. 


CHAPTER  I. 

THE  proper  foundation  of  Geology,  as  a  science, 
was  laid  by  a  German,  of  the  name  of  Lehman.  He 
observed  that  although  there  were  many  kinds  of 
rock,  they  could  all  be  referred  to  two  general 
classes.  He  likewise  observed  that  the  lowest  rocks 
exposed  to  our  observation  were  more  or  less  crys- 
talline in  their  structure,  and  contained  no  traces 
of  the  remains  of  plants  or  animals.  That  the  rocks 
lying  over  the  latter  were  generally  compact,  slaty, 
or  granular ;  and  abounded  in  the  remains  of  marine 
animals,  such  as  various  shells  and  bones,  or  with 
plants,  as  the  ferns  and  reeds.  From  the  circum- 
stances of  their  different  structure,  and  from  one 
containing  organic  remains,  or  remains  of  animals 
and  plants,  he  inferred,  that  the  lower  rocks  con. 
________  « 

By  whom  was  the  foundation  of  Geology  laid  ?  What  did 
he  observe  as  to  the  kinds  of  rock  ?  What  was  the  structure 
of  the  lower  rocks  ?  What  was  the  structure  of  the  upper 
rocks  ?  What  were  found  in  the  upper  that  were  not  in  the 
lower  rocks  ?  From  the  organic  remains  found  in  the  upper 
rocks,  what  conclusion  was  drawn  as  to  the  relative  ages  of 
the  upper  and  lower  rocks  ? 

3 


20  ELEMENTS    OF    GEOLOGY. 

taining  no  organic  remains,  were  formed  first,  from 
which  circumstance  he  called  them  primary  or 
primitive  rocks ;  and  the  others  lying  upon  the  pri- 
mary, and  containing  organic  remains,  he  called 
secondary  rocks.  The  remains  of  animals  and 
plants,  naturally  enclosed  in  the  rocks,  clays,  &c. 
are  called  organic  remains,  because  they  are  the 
remains  of  organic  bodies  ;  they  are  also  called  fos- 
sils ;  and  when  the  organic  substance  is  changed 
into  stony  matter,  they  are  called  petrifactions. 

The  ocean  has  not  always  been  confined  to  its 
present  bed,  for,  rocks  composed  mostly  of  the  re- 
mains of  various  marine  animals,  are  found  in  almost 
every  country.  The  rocks  containing  these  remains 
are  not  confined  to  detached  masses,  but  often  form 
extensive  layers,  or  strata,  as  they  are  called,  of 
many  miles,  and  often,  many  hundreds  of  miles  in 
extent.  They  not  only  occur  in  valleys,  but  they 
cap  the  highest  mountains,  and  their  thickness 
varies  from  a  few  inches  to  several  hundred  feet. 
Nearly  all  the  organic  remains,  being  those  of  ani- 
mals calculated  only  for  living  in  water,  the  sea 
must,  at  some  time,  have  covered  all  the  land  for  a 
considerable  period.  We  see  then,  that  the  relative 
levels  of  the  continents  and  ocean  must  have 


What  were  the  upper  or  fossiliferous  rocks  called  ?  What 
are  organic  remains  or  fossils?  What  are  petrifactions? 
Has  the  ocean  been  always  confined  to  its  present  bed  ?  And 
what  evidence  is  there  that  it  has  covered  all  the  land  ?  Do 
the  rocks  containing  organic  remains  occur  abundantly  in 
f  almost  every  country  ?  And  do  they  occur  of  any  great  ex- 
tent and  thickness  ?  Were  the  animals,  whose  remains  are 
found,  adapted  for  living  in  water  or  on  land  ? 


ELEMENTS    OF    GEOLOGY.  27 

changed  ;  and  one  of  two  conclusions  follows,  viz  : 
that  the  ocean  has  fallen  below  its  former  level  and 
exposed  the  dry  land,  or,  that  the  continents  have 
been  raised  and  made  to  emerge  from  the  ocean. 

If  continents  have  been  violently  elevated,  traces 
must  have  been  left  where  the  changes  of  level  have 
been  greatest,  viz.  in  the  vicinity  of  the  highest 
mountains ;  such  as  contortion,  disruption,  over- 
turned and  highly  inclined  strata.  Such  is  the  case ; 
vertical  beds  of  limestone  containing  encrinites, 
have  been  found  lying  parallel  and  in  contact  with 
coalshale, containing  canes  and  fern  leaves. 

As  respects  the  vertical  and  highly  inclined  posi- 
tion of  recomposed  beds,  it  is  admitted  that  they 
cannot  have  been  thus  deposited ;  but  must  have 
been  since  changed  in  position ;  for  it  is  physically 
impossible  to  support  an  aggregation  of  loose  gravel 
in  vertical  or  highly  inclined  planes.  [Boston  Jour- 
nal, vol.  1.  p.  243/j 

Biggsby  in  speaking  of  the  geology  of  Lake 
Huron,  says  ;  ancient  beaches  are  not  uncommon, 
at  some  distance  from  the  water,  as  on  the  Lesser 
Manitou.  It  is  'likewise  evinced  by  the  belts  of 
rolled  masses  which  gird  every  slope,  and  even  mark 
the  successive  retreats  of  the  Lake.  [Sil.  Journal, 
vol.  3.  p.  257.] 

"  The  numerous  valleys  which  furrow  the  earth's 
surface  are  highly  interesting."  The  observer 

From  observing  that  rocks  filled  with  the  marine  animals 
.  are  abundant  over  a  large  portion  of  the  earth,  what  conclu- 
sion follows  ?     What  is  the  case  respecting  the  violent  eleva- 
tion of  continents  ?     What  is  admitted  of  recomposed  beds  ? 
What  is  said  of  valleys  ? 


28  ELEMENTS    OF    GEOLOGY. 

will  remark  their  beautifully  regular  configuration, 
where  they  serve  as  channels  to  drain  the  countries 
they  traverse,  conveying  the  waters  to  "  their  final 
receptacle,  and  at  the  same  time  their  principal 
source  the  ocean."  "  Numerous  branches  ramify- 
ing over  extensive  tracts  of  country  are  collected 
into  a  principal  trunk  opening  into  some  estuary, 
and  a  regular  and  continuous  descent  is  preserved 
throughout  the  whole  course,  calculated  to  facilitate 
the  passage  of  the  waters  through  the  whole  system." 

"Now  this  configuration  is  exactly  that  which 
would  be  produced  by  the  action  of  the  waters 
scooping  out  channels  for  their  passage  in  draining 
themselves  off  from  the  face  of  a  country.  We 
may  daily  see  the  same  operation  repeated  in  min- 
iature, by  the  drainage  of  the  retiring  tide  on  mud- 
dy shores,  especially  in  confined  estuaries,  where 
the  fall  is  considerable  and  rapid."  [Conybeare 
and  Phillip 's  Geology.] 

The  proof  of  some  valleys  having  been  formed  by 
denuding  causes,  are ; 

1.  The  strata  in  the  same  planes  on  the  opposite 
sides  of  such  valleys. 

2.  The  occurrence  of  broken  fragments  of  the 
materials  which  once  filled  up  these  intervals  scat- 
tered over  the  surface. 

"  Not  only  do  we  observe  these  natural  breaches 
bearing  every  mark  of  the  violence  which  has  pro- 
duced them,  but  we  find  the  ruins  themselves  strewn 


What  of  their  configuration  ?  What  proof  have  we  that 
some  valleys  have  been  formed  by  denudation  ?  That  the 
superior  strata  has  been  swept  off  by  the  same  cause  ? 


ELEMENTS    OF    GEOLOGY.  29 

around;  immense  accumulations  of  debris,  torn 
from  the  adjacent  rocks,  and  generally  more  or  less 
rounded,  (as  if  by  attrition  against  each  other  while 
rolled  along  by  the  action  of  strong  currents,)  very 
generally  cover  the  bottom  of  the  valleys  which  tra- 
verse, and  the  plains  which  stretch  beyond  the  base 
of  the  elevated  chains.  [Boston  Journal,  i.  p.  245.] 

"  The  same  agency  that  has  excavated  valleys, 
appears  also  to  have  swept  off  the  superior  strata 
from  extensive  tracts  which  they  once  covered ; 
the  proofs  of  this  are  to  be  found  in  the  insulated 
hills,  or  outlines  of  those  strata  placed  at  conside- 
rable distances  from  their  continuous  range  with 
which  they  have  every  appearance  of  having  been 
once  connected  ;  in  the  abrupt  escarpments  which 
form  the  usual  terminations  of  strata ;  and  in  the 
very  great  quantity  of  their  debris,  scattered  fre- 
quently over  tracts  far  distant  from  those  where  they 
still  exist  in  situ.  This  stripping  off  of  the  superstrata 
is  appropriately  termed  denudation.  [Conybeare 
and  Phillip's  Geology.  Boston  Journal,  i.  p.  246.] 

We  find  the  remains  of  animals  and  plants  im- 
bedded in  the  rocks,  not  only  near  the  surface  of  the 
earth,  but  at  the  depth  of  hundreds  and  even  thou- 
sands of  feet.  Another  point  deserves  attention, 
viz :  that  these  organic  remains  are  not  of  every 
kind  jumbled  together,  but  that  particular  species 
belong  tA  particular  strata,  where  in  general,  they 
appear  to>-have  grown,  died,  and  been  imbedded. 


Are  the  organic  remains  imbedded  in  the  rocks  near  the 
surface  only  ?     Are  they  of  every  kind,  jumbled  indiscrimi- 
nately together  ?     And  how  are  they  arranged  ? 
3* 


30  ELEMENTS    OF    GEOLOGY. 

Many  of  the  rocks  are  several  hundred  feet  in  thick- 
ness, and  the  strata  of  each  exhibit  distinct  species 
and  genera  of  animals. 

The  animals  cannot  have  penetrated  through  the 
vast  masses  under  which  they  are  entombed,  and 
the  succession  of  different  animals  shows,  that  the 
strata  must  have  been  formed  in  succession,  and 
each,  must  at  some  time  have  been  the  uppermost 
stratum,  in,  and  upon  which  the  animals  were  depos- 
ited, and  afterwards  covered  by  succeeding  strata. 

In  the  lower  secondary  rocks,  the  organic  remains 
are  almost  entirely  different  from  the  existing  ge- 
nera and  species  of  animals  and  plants  ;  and  in  pro- 
portion as  the  rocks  are  of  more  recent  origin,  lying 
successively  upon  the  lower  ones,  the  fossils  ap- 
proach more  and  more  nearly  to  the  animals  and 
plants  in  existence. 

•  The  fossil  remains  of  animals,  not  now  in  exis- 
tence, entombed  in  the  solid  rocks,  present  us  with 
durable  monuments  of  the  great  revolutions  which 
the  earth  has  undergone  at  remote  periods  of  time, 
and  open  to  us  a  new  page  for  our  study  and  inves- 
tigation in  the  great  book  of  nature. 

The  period  of  time  required  to  produce  the  effects 
observed  in  the  fossiliferous  rocks  must  have  been 


Do  the  animals  appear  to  have  penetrated  through  the 
masses  under  which  they  are  found  ?  And  what  does  the 
succession  of  different  animals  in  the  different  strata  show  ? 
Are  the  animals  in  the  lower  secondary  rocks,  similiar  to 
those  now  existing  ?  In  the  most  recent  rocks  do  the  organic 
remains  approach  more  nearly  to  the  animals  and  plants  now 
existing  ?  What  do  the  fossiJ  remains  show  us  ?  Does  any 
great  period  of  time  appear  to  have  been  required  to  produce 
the  observed  results  ? 


ELEMENTS    OF    GEOLOGY.  31 

very  great.  Clearly,  that  was  not  a  temporary  in- 
undation like  the  deluge,  the  evidences  of  which  we 
see  every  where  on  the  surface  of  the  earth  ;  but,  it 
would  seem,  must  have  continued  for  almost  count- 
less  ages. 

This  may  at  first  seem  to  clash  with  the  Mosaic 
account  of  the  creation  of  the  world ;  but  instead 
of  that,  geology  offers  incontestable  evidence  of  the 
truth  of  the  Mosaic  account.  The  order  which  this 
account  assigns  to  the  different  epochs  of  creation,  is 
precisely  the  same  as  that,  which  has  been  deduced 
from  geological  considerations. 

Geology  is  a  science  which  has  been  thought  by 
many  persons  to  draw  conclusions  at  variance  with 
the  Book  of  Genesis  ;  but,  "  when  at  last  more  ma- 
tured by  a  series  of  careful  observations  and  legiti- 
mate induction,  it  teaches  us  precisely  what  Moses 
had  taught  more  than  three  thousand  years  ago." 
[SiHimcLfl?  s  Journal^ 

In  construing  day,  in  the  Mosaic  account  of  the 
creation,  periods  of  time  of  indefinite  duration  must 
be  substituted.  The  reader  who  may  have  any 
doubts  upon  this  interpretation  of  the  term  day,  is 
referred  to  the  American  Journal  of  Science,  Vol. 
XXV.  pages  30 — 41,  where  a  full  exposition  of  the 
terms  employed  in  1st.  of  Genesis  is  given,  indepen- 
dent of  geological  considerations. 

All  geologists,  or  at  least  the  largest  portion  ^of 


Do  we  see  evidences  of  the  deluge,  as  well  as  of  other  con- 
vulsions and  inundations  ?  From  geological  phenomena  how 
is  the  term  day  explained,  as  used  in  the  Mosaic  account  of 
the  creation  of  the  world  ?  Does  geology  serve  to  prove  any 
part  of  the  sacred  writings  ? 


32  ELEMENTS    OF    GEOLOGY. 

them  admit,  that  the  discoveries  of  geology  are  con- 
sistent with  the  Mosaic  History.  The  following 
extract  from  Bakewell's  Geology  bears  in  some  de- 
gree upon  the  same  point. 

"  The  six  days  in  which  Creative  Energy  reno- 
vated the  globe,  and  called  into  existence  different 
classes  of  animals,  will  imply  six  successive  epochs, 
of  indefinite  duration.  The  absence  of  human  bones 
in  stratified  rocks,  or  in  undisturbed  beds  of  gravel 
or  clay,  indicates  that  man,  the  most  perfect  of  ter- 
restrial beings,  was  not  created  till  after  those  great 
revolutions,  which  buried  different  classes  and  en- 
tire genera  of  animals,  deep  under  the  present  sur- 
face of  the  earth. 

That  man  is  the  latest  tenant  of  the  globe,  is  con- 
firmed by  the  oldest  records  or  traditions  that  exist 
of  the  origin  of  the  human  race. 

The  great  convulsions  which  have  changed  the 
ancient  surface  of  the  globe,  and  reduced  it  to  its 
present  habitable  state,  were  not,  it  is  reasonable  to 
believe,  effected  by  the  blind  fury  of  tumultuous  and 
conflicting  elements,  but  were  the  result  of  deter- 
mined laws,  directed  by  the  same  wisdom  which  reg- 
ulates every  part  of  the  external  universe. 

Compared  with  the  ephemeral  existence  of  mac 
on  the  earth,  the  epochs  of  these  changes  may  ap- 
pear of  almost  inconceivable  duration ;  but  we  are 
expressly  told,  that  with  the  Creator  "  a  thousand 
years  are  as  one  day,  and  one  day  as  a  thousand." 


What  geological  phenomenon  shows  that  man  is  the  ani 
mal  last  formed  upon  the  earth  ?  Do  the  oldest  records  anc 
traditions  prove  the  same  thing  ? 


ELEMENTS    OF    GEOLOGY.  33 


Geological  Discoveries  Consistent  with  the  Bible. 

"  It  may  seem  just  matter  of  surprise,  that  many 
learned  and  religious  men,  should  regard  with  jeal- 
ousy and  suspicion,  the  study  of  any  natural  phenom- 
ena which  abound  with  proofs  of  some  of  the 
highest  attributes  of  the  Deity  ;  and  should  receive 
with  distrust,  or  total  incredulity,  the  announce- 
ment of  conclusions  which  the  geologist  deduces 
from  a  careful  and  patient  investigation  of  facts 
which  it  is  his  province  to  explore. 

These  doubts  and  difficulties,  result  from  the  dis- 
closures made  by  geology  respecting  the  lapse  of 
very  long  periods  of  time  before  the  creation  of  man. 
Minds  which  have  long  been  accustomed  to  date  the 
origin  of  the  universe,  as  well  as  that  of  the  human 
race,  from  an  era  of  about  six  thousand  years  ago, 
receive  with  reluctance  any  information,  which  if 
true,  demands  some  new  modification  of  their  pres- 
ent ideas  of  cosmogony ;  and,  as  in  this  respect,  geol- 
ogy has  shared  the  fate  of  other  infant  sciences,  in 
being  for  a  while  considered  hostile  to  revf  ,Jed  reli- 
gion ;  so  like  them,  when  fully  understood,  it  will  be 
found  a  potent  and  consistent  auxiliary  to  it,  exalt- 
ing our  conviction  of  the  power  and  wisdom  and 
goodness  of  the  Creator. 

No  reasonable  man  can  doubt  that  all  the  pheno- 
mena of  the  natural  world  derive  their  origin  from 
God ;  and  no  one  who  believes  the  bible  to  be  the 


What  do  the  doubts  respecting  geology  result  from  ? 
what  will  geology  when  understood  be  found  auxiliary  ? 


34  ELEMENTS    OF    GEOLOGY. 

word  of  God,  has  cause  to  fear  any  discrepancy  be- 
tween his  word  and  the  results  of  any  new  discov- 
eries respecting  the  nature  of  his  works ;  but  the 
early  and  deliberative  stages  of  scientific  discovery 
are  always  those  of  perplexity  and  alarm,  and  during 
these  stages  the  human  mind  is  naturally  circum- 
spect, and  slow  to  admit  any  new  conclusions  in 
any  department  of  knowledge. 

The  prejudiced  persecutors  of  Galileo  apprehend- 
ed danger  to  religion,  from  the  discoveries  of  a 
science,  in  which  a  Kepler,  and  a  Newton  found  de- 
monstration of  the  most  sublime  and  glorious  attri- 
butes of  the  Creator. 

A  Herschel  has  pronounced  that  Geology  in  the 
magnitude  and  sublimity  of  the  objects  of  which  it 
treats,  undoubtedly  ranks  in  the  scale  of  sciences 
next  to  astronomy  ;  and  the  history  of  the  structure 
of  our  planet,  when  it  shall  be  fully  understood,  must 
lead  to  the  same  great  moral  results  that  have  fol- 
lowed the  study  of  the  mechanism  of  the  heaven?, 

Geology  has  already  proved  by  physical  evidence, 
that  the  surface  of  the  globe  has  not  existed  in  its 
actual  state  from  eternity,  but  has  advanced  through 
a  series  of  creative  operations  succeeding  each  other 
at  long  and  indefinite  intervals  of  time  ;  that  a*ll  the 
actual  combinations  of  matter  have  had  a  prior  exis- 
tence in  some  other  state ;  and  that  the  ultimate 
atoms  of  the  material  elements  through  whatever 
changes  they  may  have  passed,  are,  and  ever  have 


What  science  does  geology  rank  next  to  ?     What  has  it 
already  proved  ?     What  do  these  results  accord  with  ? 


ELEMENTS    OF   GEOLOGY.  35 

been,  governed  by  laws  as  regular  and  uniform,  as 
those  which  hold  the  planets  in  their  course. 

All  these  results  entirely  accord  with  the  best  feel- 
ings of  our  nature  arid  with  our  rational  conviction 
of  the  greatness  and  goodness  of  the  Creator  of  the 
universe.  The  reluctance  with  which  evidences 
of  such  high  importance  to  natural  theology,  have 
been  admitted  by  many  persons  who  are  sincerely 
zealous  for  the  interests  of  religion,  can  only  be  ex- 
plained by  their  want  of  accurate  information  in 
physical  science ;  and  by  their  ungrounded  fears, 
lest  natural  phenomena  should  prove  inconsistent 
with  the  account  of  Creation  in  the  book  of  Ge- 
nesis. 

It  was  assuredly  prudent  in  the  infancy  of  Geo- 
logy, and  during  the  immature  state  of  those  phys- 
ical sciences  which  form  its  only  sure  foundation, 
not  to  enter  upon  any  comparison  of  the  Mosaic 
account  of  the  Creation,  with  the  structure  of  the 
earth,  then  almost  entirely  unknown  ;  the  time  was 
not  then  come  when  the  knowledge  of  natural  phe- 
nomena was  sufficiently  advanced  to  admit  of  anjr 
profitable  investigation  of  this  question ;  but  the 
discoveries  of  the  last  half  century  have  been  so  ex- 
tensive in  this  department  of  natural  knowledge, 
that,  whether  we  will  or  not,  the  subject  is  now 
forced  upon  our  consideration,  and  can  no  longer 
escape  discussion.  , 

The  truth  is,  that  all  observers,  however  various 


When  was  it  prudent  to  refrain  from  a  comparison  of  geo- 
logical deductions  with  the  Mosaic  account  of  the  earth  ? 
Why  is  the  question  now  forced  upon  us  ?  What  is  admitted 
by  all  observers  ? 


36  ELEMENTS    OF    GEOLOGY. 

may  be  their  speculations,  respecting  the  secondary 
causes  by  which  geological  phenomena  have  been 
brought  about,  are  now  agreed  in  admitting  the  lapse 
of  very  long  periods  of  time  to  have  been  an  essen- 
tial condition  to  the  production  of  these  phenomena. 

The  disappointment  of  those  who  look  for  a  de- 
tailed account  of  geological  phenomena  in  the  bible, 
rests  on  the  gratuitous  expectation  of  finding  there- 
in historical  information,  respecting  all  the  opera- 
tions of  the  Creator  in  times  and  places  with  which 
the  human  race  has  no  concern ;  as  reasonably 
might  we  object  that  the  Mosaic  history  is  imper- 
fect, because  it  makes  no  specific  mention  of  the 
satellites  of  Jupiter,  or  the  rings  of  Saturn,  as  feel 
disappointment  at  not  finding  in  it  the  history  of 
geological  phenomena,  the  details  of  which  may  be 
fit  matter  for  a  scientific  encyclopedia,  but  are 
foreign  to  the  objects  of  a  volume  intended  only  to 
be  a  guide  of  religious  belief  and  moral  conduct. 

We  may  fairly  ask  of  those  persons  who  consid- 
er physical  science  a  fit  subject  for  revelation,  what 
point  they  can  imagine  short  of  a  communication 
of  Omniscience  at  which  such  a  revelation  might 
have  stopped  without  imperfections  of  omission  less 
in  degree,  but  similar  in  kind,  to  that  which  they 
impute  to  Moses  ? 

A  revelation  of  so  much  only  of  astronomy  as  was 
known  to  Copernicus,  would  have  seemed  imperfect 
after  the  discoveries  of  Newton ;  and  a  revelation  of 


What  is  said  of  those  who  look  for  a  detailed  account  of 
geological  phenomena  in  the  bible  ?  What  question  may  we 
fuirly  ask  such  persons  ?  What  is  said  of  the  astronomy  of 
Copernicus?  and  of  that  of  Newton? 


ELEMENTS    OF    GEOLOGY.  37 

the  science  of  Newton  would  have  appeared  defec- 
tive to  La  Place ;  a  revelation  of  all  the  chemical 
knowledge  of  the  18th  century  would  have  been  as 
deficient  in  comparison  with  the  information  of  the 
present  day,  as  what  is  now  known  in  this  science 
will  probably  appear  before  the  termination  of  an- 
other age. 

In  the  whole  circle  of  sciences  there  is  not  one  to 
which  this  argument  may  not  be  extended,  until  we 
should  require  from  revelation  a  full  developement 
of  all  the  mysterious  agencies  that  uphold  the  me- 
chanism of  the  material  world.  Such  a  revelation 
might  indeed  be  suited  to  beings  of  a  more  exalted 
order  than  mankind,  but  unless  human  nature  had 
been  constituted  otherwise  than  it  is,  the  above 
supposed  communication  of  Omniscience  would 
have  been  imparted  to  creatures  utterly  incapable  of 
receiving  it,  under  the  present  moral  or  physical 
condition  of  the  human  race  ;  and  would  have  been 
also  at  variance  with  the  design  of  all  God's  other 
disclosures  of  himself,  the  end  of  which  has  uniformly 
been,  not  to  impart  intellectual  but  moral  know- 
ledge." [Buckland's  Geology,  vol.  i.] 

"  Sound  philosophy  and  revealed  religion  are  na- 
turally connected  with  each  other.  However  widely 
they  may  differ  as  to  the  manner  in  which  they 
severally  proceed,  they  are  both  tending  towards  one 


What  of  the  chemical  knowledge  of  the  18th  century? 
How  far  may  this  argument  be  extended?  To  whom 
would  such  a  revelation  be  suited  ?  What  appears  to  be  the 
end  of  God's  disclosures  of  himself?  To  what  do  sound  phi- 
losophy  and  revealed  religion  tend  ? 
4 


38  ELEMENTS    OF    GEOLOGY. 

common  object,  the  establishment  of  truth.  Philos- 
ophy sets  out  in  its  pursuit  of  this  object  from  the 
lowest  point — Religion  from  the  highest :  the  for- 
mer begins  with  the  last  effect,  the  latter  commences 
with  the  first  cause. 

Geology  and  religion  are  inevitably  brought  in 
contact  on  the  great  point  of  the  creation  of  the 
world,  and  it  appears  highly  desirable  to  ascertain 
if  the  facts  of  geology  and  the  Mosaic  account  of 
the  creation  are  not  reconcilable  with  each  other. 

The  commonly  received  opinions  of  the  Mosaic 
account,  are  at  variance  with  the  inferences  deduced 
from  the  researches  of  geology. 

It  will  probably  occur  to  most  Christians  that 
they  can  recollect  the  time  when  they  supposed  that 
every  night  and  day  mentioned  in  the  first  chapter 
of  Genesis,  must  be  understood  to  mean  periods  of 
twenty-four  hours,  though  there  can  be  no  doubt 
that  Moses  did  not  intend  such  restriction.  Critics 
also  inform  us  that  his  words  ought  not  to  have 
been  thus  translated. 

We  are  told  that  the  word  day  does  in  fact  signify 
an  indefinite  period  of  time,  and  common  sense 
ought  to  bring  us  to  the  same  conclusion  in  regard 
to  the  three  first  days,  for  the  text  says,  that  the  sun, 
moon,  and  stars,  were  placed  in  the  firmament  to 
divide  the  day  from  the  night. 

Moses  is  generally  supposed  to  give  a  particular 
description  of  the  creation  of  the  world  out  of  no- 


How  does  philosophy  set  out  ?  From  what  point  does  re- 
ligion  start  ?  What  is  highly  desirable  to  ascertain  ?  What 
is  said  of  the  first  chapter  of  Genesis  ?  What  is  Moses  gene- 
rally supposed  to  give  ? 


ELEMENTS    OF    GEOLOGY.  39 

thing,  and  to  fix  the  date  of  the  creation  at  a  period, 
either  immediately  previous  to,  or  contemporary 
with,  the  three  first  days  afterwards  mentioned. 

These  suppositions  are  gratuitous.  All  that 
Moses  says  of  the  creation  is : 

1.  That  it  was  created  by  God,  and: 

2.  That  this  creation  took  place  in  the  beginning. 

Nothing  can  be  more  positive  than  the  first  decla- 
ration, or  more  indefinite  that  the  second."  [Man- 
telPs  Geology  of  Sussex,  p.  1  to  3.] 

"  Does  Moses  ever  say,  that  when  God  created  the 
the  heavens  and  the  earth  he  did  more  at  the  time 
alluded  to  than  transform  them  out  of  pre-existing 
materials  ?  or  that  there  was  not  an  interval  of  many 
ages  between  the  first  act  of  creation  at  the  begin- 
ning, and  those  more  detailed  operations,  the  account 
of  which  commences  at  the  second  verse,  and  which 
are  described  to  us  as  having  been  performed  in  so 
many  days  ? 

Or  finally,  does  he  ever  make  us  to  understand 
that  the  genealogies  of  man  went  any  farther  than 
to  fix  the  antiquity  of  the  human  species,  and  of  con- 
sequence that  they  left  the  antiquity  of  the  globe  a 
free  subject  for  the  speculation  of  philosophers." 
[Chalmer's  Evidence  of  the  Christian  Revelation.'] 

"It  has  long  been  matter  of  discussion  among 
learned  theologians  whether  the  first  verse  of  Gen- 
esis should  be  considered  prospectively,  as  contain- 
ing a  summary  announcement  of  that  new  creation, 


Are  those  suppositions  correct  ?  What  questions  are  those 
respecting  Moses  ?  What  has  long  been  a  point  of  discus- 
sion among  learned  theologians  ? 


40  ELEMENTS    OF    GEOLOGY. 

the  details  of  which  follow  in  the  record  of  the  ope- 
rations  of  the  six  successive  days ;  or  as  an  abstract 
statement,  that  the  heaven  and  the  earth  were  made 
by  God,  without  limiting  the  period  when  the  crea- 
tive agency  was  exerted.  The  latter  of  these  opin- 
ions is  in  perfect  harmony  with  the  discoveries  of 
geology. 

The  Mosaic  narrative  commences  with  a  decla- 
ration, that  '  In  the  beginning  God  created  the  hea- 
ven and  earth.' 

These  few  first  words  of  Genesis  may  be  fairly 
appealed  to  by  the  geologist  as  containing  a  brief 
statement  of  the  creation  of  the  material  elements, 
at  a  time  distinctly  preceding  the  operations  of  the 
first  day ;  it  is  nowhere  affirmed  that  God  created 
the  heaven  and  the  earth  in  the  first  day,  but  in  the 
beginning ;  this  beginning  may  have  been  an  epoch 
at  an  unmeasured  distance,  followed  by  periods  of 
undefined  duration,  during  which  all  the  physical 
operations  disclosed  by  geology  were  going  on. 

The  first  verse  of  Genesis,  therefore,  seems  ex- 
plicitly to  assert  the  creation  of  the  Universe  ;  *  the 
heaven,'  including  the  siderial  systems,  and  <the 
earth'  more  especially  specifying  our  planet,  on  the 
subsequent  scene  of  the  operations  of  the  six  days 
about  to  be  described :  no  information  is  given  as 
to  the  events  \vhich  may  have  occurred  upon  this 
earth,  unconnected  with  the  history  of  man  between 


What  opinion  is  in  harmony  with  the  discoveries  of  geol. 
ogy  ?  What  may  be  appealed  to  by  geologists  ?  What  may 
the  beginning  have  been  ?  What  does  the  first  verse  of  Ge. 
nesis  assert  ? 


ELEMENTS    OF   GEOLOGY.  41 

the  creation  of  its  component  matter,  recorded  in  the 
first  verse,  and  the  era  at  which  its  history  is  re* 
sumed  in  the  second  verse ;  nor  is  any  limit  fixed 
to  the  time  during  which  these  intermediate  events 
may  have  been  going  on. 

Millions  of  millions  of  years  may  have  occupied 
the  indefinite  period  between  the  beginning  in  which 
God  created  the  heaven  and  the  earth,  and  the  even- 
ing or  commencement  of  the  first  day  of  the  Mosaic 
narrative. 

The  second  verse  may  describe  the  condition  of 
the  earth  on  the  evening  of  this  first  day,  (for  in 
the  Jewish  mode  of  computation  used  by  Moses, 
each  day  is  reckoned  from  the  beginning  of  one 
evening  to  the  beginning  of  another  evening.) 

This  first  evening  may  be  considered  as  the  ter- 
mination of  the  indefinite  time  which  followed  the 
primeval  creation,  announced  in  the  first  verse,  as 
the  commencement  of  the  first  six  succeeding  days, 
in  which  the  earth  was  to  be  fitted  up  and  peopled 
in  a  manner  fit  for  the  reception  of  mankind. 

We  have  in  this  second  verse  a  distinct  mention 
of  earth  and  waters,  as  already  existing  and  involved 
in  darkness ;  their  condition  also  is  described  as  a 
state  of  confusion  and  erupting,  (tohu  bohu)  words 
which  are  usually  interpreted  by  the  vague  and  in- 
definite Greek  term  *  chaos,'  and  which  may  be 


What  time  may  have  elapsed  between  the  periods  spoken 

of  in  the  first  verse,  and  that  in  the  second  ?     What  may 

the  second  verse  describe  ?     What  may  the  first  evening  be 

considered  ?    What  peculiar  words  occur  in  the  second  verse  7 

4* 


42  ELEMENTS    OF   GEOLOGY. 

geologically  considered  as  designating  the  wreck 
and  ruins  of  a  former  world. 

At  this  intermediate  point  of  time,  the  preceding 
undefined  geological  periods  had  terminated,  a  new 
series  of  events  commenced,  and  the  work  of  the 
first  morning  of  this  new  creation  was  the  calling 
forth  of  light  from  this  temporary  darkness,  which 
had  overspread  the  ruins  of  the  ancient  earth. 

Prof.  Pussey  remarks  that  the  words  'let  there  be 
light'  by  no  means  imply  that  light  had  not  before 
existed. 

We  have  mention  of  the  ancient  earth  and  ancient 
sea  in  the  ninth  verse,  in  which  the  waters  are  com- 
manded to  be  gathered  together  into  one  place,  and 
the  dry  land  to  appear ;  this  dry  land  being  the  same 
earth  whose  material  creation  had  been  announced 
in  the  first  verse,  and  whose  temporary  submersion, 
and  temporary  darkness,  are  described  in  the  second 
verse ;  the  appearance  of  the  land  and  the  gather- 
ing together  of  the  waters  are  the  only  facts  affirm- 
ed respecting  them  in  the  ninth  verse,  but  neither 
land  nor  waters  are  said  to  have  been  created  on  the 
third  day. 

A  similar  interpretation  may  be  given  of  the  four- 
teenth and  four  following  verses.  What  is  herein 
stated  of  the  celestial  luminaries  seems  to  be  spoken 
solely  with  reference  to  our  planet,  and  more  espe- 
cially to  the  human  race  then  about  to  be  placed 
upon  it. 


How  may  they  be  geologically  designated  ?  What  is  said 
of  the  words  « let  there  be  light  ?'  What  is  mentioned  in  the 
ninth  verse  ? 


ELEMENTS    OF    GEOLOGY.  43 

We  are  not  told  that  the  substance  of  the  sun  and 
moon  were  first  called  into  existence  on  the  fourth 
day.  The  text  may  equally  imply  that  these  bodies 
were  then  prepared  and  appointed  to  certain  offices 
of  high  importance  to  mankind  ;  to  give  light  upon 
the  earth  and  to  rule  over  the  day  and  over  the  night ; 
*  to  be  for  signs  and  for  seasons  and  for  days  and  for 
years.'  The  fact  of  their  creation  had  before  been 
stated  in  the  first  verse. 

'The  stars  also'  are  mentioned  (Gen.  i.  16.)  in 
three  words  only,  almost  parenthetically  ;  as  if  for 
the  sole  purpose  of  announcing  that  they  also  were 
made  by  the  same  Power  as  those  luminaries  which 
are  more  important  to  us,  the  sun  and  the  moon. 

This  very  slight  notice  of  the  countless  host  of 
celestial  bodies,  all  of  which  are  probably  suns,  the 
centres  of  other  planetary  systems  whilst  our  little 
satillite,  the  moon,  is  mentioned  as  next  in  impor- 
tance to  the  sun,  shows  clearly  that  -astronomical 
phenomena  are  here  spoken  of  only  according  to 
their  relative  importance  to  our  earth  and  to  man- 
kind, and  without  any  regard  to  their  real  impor- 
tance in  the  boundless  universe. 

It  seems  impossible  to  include  the  fixed  stars 
among  those  bodies  which  are  said  (Gen.  i.  17.)  to 
have  been  set  in  the  firmament  of  the  heaven  to  give 
light  upon  the  earth ;  since  without  the  aid  of  teles- 
copes, by  far  the  greater  number  of  them  are  invis- 
ible. The  same  principle  seems  to  pervade  the 


What  is  said  of  the  sun,  moon,  and  stars  ?  What  shows 
that  these  are  mentioned  only  according  to  their  relative  im- 
portance to  the  earth?  What  is  said  of  the  fixed  stars? 
What  difficulties  are  solved  by  this  interpretation  ? 


44  ELEMENTS   OF   GEOLOGY. 

description  of  creation  which  concerns  our  planet ; 
the  creation  of  its  component  matter  having  been 
announced  in  the  first  verse,  the  phenomena  of  geo- 
logy like  those  of  astronomy,  are  passed  over  in 
silence,  and  the  narrative  proceeds  at  once  to  de- 
tails of  the  actual  creation  which  have  more  im- 
mediate reference  to  man. 

The  interpretation  here  proposed,  seems  more- 
over, to  solve  the  difficulty  which  would  otherwise 
attend  the  statement  of  the  appearance  of  light  on 
the  first  day,  while  the  sun  and  moon  and  stars  were 
not  made  to  appear  until  the  fourth  day. 

If  we  suppose  all  the  heavenly  bodies  and  the  earth 
to  have  been  created  at  the  indefinitely  distant  time 
designated  by  the  word  beginning,  and  that  the  dark- 
ness described  on  the  evening  of  the  first  day,  was 
a  temporary  darkness,  produced  by  an  accumula- 
tion of  dense  vapours  '  upon  the  face  of  the  deep,'  an 
incipient  dispersion  of  these  vapours  may  have  re- 
admitted light  to  the  earth  upon  the  first  day,  whilst 
the  exciting  cause  of  light  was  still  obscured,  and 
the  farther  purification  of  the  atmosphere  upon  the 
fourth  day,  may  have  caused  the  sun,  moon,  and  stars, 
to  re-appear  in  the  firmament  of  heaven,  to  assume 
their  new  relations  to  the  newly  modified  earth,  and 
to  the  human  race. 

We  have  evidence  of  the  presence  of  light  during 
long  and  distant  periods  of  time,  in  which  the  many 


What  is  the  supposition  respecting  the  heavenly  bodies  and 
the  earth?  What  is  said  of  the  first  day?  What  of  the 
fourth  day  ?  What  is  evidence  of  the  presence  of  light  dur- 
ing long  and  distant  periods  of  time  ? 


ELEMENTS    OF    GEOLOGY  45 

extinct  fossil  forms  of  life  succeeded  one  another 
upon  the  early  surface  of  the  globe.  This  evidence 
consists  in  the  petrified  remains  of  the  eyes  of  ani- 
mals found  in  geological  formations  of  various  ages. 

The  eyes  of  the  Trilobites  are  beautifully  preserved 
in  the  transition  rocks,  and  were  constructed  so  as 
to  bear  a  remarkably  close  resemblance  to  those  of 
existing  crustaceous  animals. 

The  eyes  of  the  Ichthyosaurus  of  the  Lias  con- 
tained  an  apparatus  so  similar  to  that  of  many  birds, 
as  to  leave  no  doubt  that  they  were  optical  instru- 
ments, and  calculated  to  receive  impressions  and 
convey  sensations  of  sight  to  living  animals.  This 
conclusion  is  farther  strengthened  by  the  general 
fact,  that  the  heads  of  all  fossil  fishes  and  reptiles,  in 
every  geological  formation,  are  furnished  with  cavi- 
ties for  the  reception  of  eyes,  and  with  perforations 
for  the  passage  of  optic  nerves,  although  the  in- 
stances are  rare  in  which  any  part  of  the  eye  itself 
has  been  preserved. 

The  influence  of  light  is  also  so  necessary  to  the 
growth  of  existing  vegetables  that  we,  cannot  but  in- 
fer, that  it  was  equally  essential  to  the  developement 
of  the  numerous  fossil  species  of  the  vegetable  king- 
dom which  are  co-extensive  and  co-eval  with  the  re- 
mains of  fossil  animals. 

In  conclusion  it  should  be  recollected  that  the 


What  are  preserved  in  the  transition  rocks?  What  do 
they  resemble  ?  What  contained  an  apparatus  ?  To  what 
were  they  similar  ?  For  what  are  they  calculated  ?  What  gene- 
ral fact  is  spoken  of?  What  conclusion  is  strengthened  by 
this  general  fact  ?  What  would  you  infer  from  the  influence 
of  light? 


46  ELEMENTS    OF    GEOLOGY. 

question  is  not  respecting  the  correctness  of  the 
Mosaic  narrative,  but  of  our  interpretation  of  it ;  and 
still  further,  it  should  be  borne  in  mind  that  the  ob- 
ject of  this  account  was,  not  to  state  in  what  man- 
ner, but  by  whom,  the  world  was  made. 

As  the  prevailing  tendency  of  men  in  those  early 
days  was  to  worship  the  most  glorious  objects  of 
nature,  viz.  the  sun,  moon  and  stars ;  it  should  seenj 
to  have  been  one  important  point  in  the  Mosaic  ae* 
count  of  creation,  to  guard  the  Israelites  against  the 
Polytheism  and  idolatry  of  the  nations  around  them ; 
by  announcing  that  all  these  magnificent  celestial 
bodies  were  no  gods,  but  the  works  of  one  Almighty 
Creator  to  whom  alone  the  worship  of  mankind  is 
due.  [BucklancFs  Geology.] 

Professor  Sedgwick,  in  his  eloquent  and  admirable 
discourse  on  the  studies  of  the  University  of  Cam- 
bridge in  1833,  in  which  he  ably  points  out  the  rela- 
tions  which  geology  bears  to  natural  religion,  thus 
sums  up  his  valuable  opinion  as  to  the  kind  of  in- 
formation we  ought  to  look  for  in  the  bible  : — 

"  The  Bible  instructs  us  that  man,  and  other  living 
things  have  been  placed  but  a  few  years  upon  the 
earth ;  and  the  physical  monuments  of  the  world 
bear  witness  to  the  same  truth :  if  the  astronomer 
tells  us  of  myriads  of  worlds  not  spoken  of  in  the 
Sacred  records ;  the  geologist,  in  like  manner  proves 
(not  by  arguments  from  analogy,  but  by  the  incon- 
trovertible evidence  of  physical  phenomena,)  that 


Respecting  what  should  the  question  be  ?  What  is  the  ob- 
ject of  this  account  ?  What  seems  to  be  an  important  point 
in  the  Mosiac  account  of  creation  ?  In  what  does  the  Bible 
instruct  us  ?  In  what  does  geology  ? 


ELEMENTS    OF    GEOLOGY.  47 

there  were  former  conditions  of  our  planet,  separated 
from  each  other  by  vast  intervals  of  time,  during 
which  man,  and  the  other  creatures  of  his  own  date, 
had  not  been  called  into  being. 

Periods  such  as  these  belong  not,  therefore,  to  the 
moral  history  of  our  race,  and  come  neither  within 
the  letter,  nor  the  spirit  of  revelation.  Between  the 
first  creation  of  the  earth,  and  the  day  in  which  it 
pleased  God  to  place  man  upon  it,  who  shall  dare 
to  define  the  interval  ? 

On  this  question  scripture  is  silent,  but  that  silence 
destroys  not  the  meaning  of  those  physical  monu- 
ments of  his  power  that  God  has  put  before  our  eyes, 
giving  us  at  the  same  time  faculties  whereby  we 
may  interpret  them,  and  comprehend  their  meaning." 
[BucHand's  Geology,  i.  p.  34.] 


CHAPTER  II. 

Every  one  must  have  observed  that  the  mineral 
substances  upon  the  surface  of  the  Earth,  differ 
much  in  their  hardness,  weight,  colour,  and  other 
qualities. 

The  different  minerals  appear  at  first  so  nume- 1* 
rous  as  to  make  it  difficult  to  become  familiar  with 
them,  but  on  examination  it  is  found,  that  the  num- 


On  what  question  is  scripture  silent?  Do  the  mineral 
bodies  differ  much  in  their  qualities  ?  Do  they  appear  very 
numerous  ?  and  are  they  as  numerous  as  they  appear  to  be  ? 


48  ELEMENTS    OF    GEOLOGY. 

her  of  minerals  is  not  very  great,  and  the  elemen- 
tary substances  composing  them  still  less. 

The  bodies  called  elementary  or  simple  bodies, 
are  those  that  have  never  as  yet  been  decomposed 
into  two  or  more  other  bodies,  as  for  instance,  gold, 
silver,  tin,  copper,  lead,  sulphur,  &c. 

The  whole  number  of  the  elementary  substances 
forming  all  the  minerals,  rocks,  plants,  animals,  and 
every  thing  we  can  see  upon  or  in  the  earth,  is  only 
about  fifty-four. 

The  elementary  substances  entering  into  combi- 
nation* with  each  other  to  form  the  principal  part  of 
the  mass  of  the  globe,  are, 

OXYGEN;        SILICON;     ALUMINUM;     POTASSIUM; 
CHLORINE;    CARBON;    CALCIUM;        SODIUM; 
HYDROGEN;  SULPHUR;  MAGNESIUM;  IRON. 

Oxygen  is  the  most  common  substance  existing 
in  combination  with  other  bodies,  and  is  supposed 
to  constitute  about  one  half  of  the  whole  weight  of 
the  materials  on  the  surface  of  the  globe.  By  its 
combination  with  silicon  it  forms  silex,  which  enters 


What  are  elementary  or  simple  bodies  ?  What  is  about 
the  number  of  simple  bodies  ?  Are  all  substances  formed  of 
those  few  simple  bodies?  What  are  the  elementary  sub. 
stances  that  form  almost  all  the  mass  of  the  globe  as  far  as 
we  know  ?  Which  of  these  is  most  common  in  combination 
with  other  bodies  ?  About  what  proportion  of  the  weight  of 
the  bodies  of  the  Earth,  is  oxygen  supposed  to  constitute  ? 
What  does  it  form  by  combining  with  silicon  ? 

*  Substances  are  said  to  combine,  when  they  unite  with  each  other 
so  as  to  change  their  properties.  Thus  potassa  or  soda,  by  union  with 
oil  or  grease,  form  soap,  a  substance  totally  different  from  the  bodies 
of  which  it  is  formed. 


ELEMENTS    OF    GEOLOGY.  49 

into  most  of  the  minerals  and  rocks  in  large  pro- 
portion. 

Oxygen  combined  with  hydrogen  forms  water. 
With  carbon,  it  forms  invisible  elastic  bodies  like 
air,  but  which  if  breathed  destroy  life.  With  sul- 
phur it  forms  acids,*  one  of  which  is  used  in  bleach- 
ing straw,  and  which  you  always  smell  when  sul- 
phur is  burnt  in  the  air ;  another  of  these  acids  is 
called  sulphuric  acid,  and  oil  of  vitriol. 

Oxygen  unites  with  aluminum,  calcium,  magne- 
sium, potassium,  and  sodium,  which  are  metals,  and 
forms  with  the  first  alumina,  which  exists  abun- 
dantly in  the  clays  and  slates ;  with  calcium  it  forms 
lime,  with  magnesium  magnesia,  with  potassium 
potash,  and  with  sodium  soda,  and  with  iron  it  forms 
the  common  ores  of  iron. 

Oxygen  is  contained  in  large  proportion  in  the 
air,  and  it  is  that  which  supports  life  by  our  breath- 
ing. It  is  for  want  of  oxygen  that  persons  die  soon 


What  does  it  form  by  uniting  with  hydrogen  ?  What  does 
It  form  when  combined  with  carbon  ?  What  effect  is  pro. 
duced  by  breathing  those  compounds  ?  When  oxygen  unites 
with  sulphur  what  are  formed  ?  For  what  is  one  of  these 
acids  used  and  what  is  its  odour  ?  What  is  the  other  acid 
called  ?  When  oxygen  unites  with  aluminum,  what  is  formed, 
and  in  what  does  alumina  exist  abundantly?  What  are 
formed  by  the  union  of  oxygen  with  calcium,  magnesium, 
potassium,  sodium,  and  with  iron  ?  In  what  is  oxygen  found 
in  large  proportion  ?  What  must  be  in  the  air,  to  support 
life  when  we  breath  it  ?  Why  is  it  that  persons  drown  under 
water  ? 

t  Acids  are  generally  sour  to  the  taste,  and  by  their  combination 
•with  other  bodies,  they  form  substances  differing  both  from  the  acidL 
and  the  other  body. 

5 


50  ELEMENTS    OF   GEOLOGY. 

when  under  water.  Most  bodies  when  uniting  with 
oxygen,  burn,  or  give  out  light  and  heat. 

It  is  owing  to  the  combination  of  oxygen  with 
other  substances,  that  oil,  tallow,  and  wood  burn. 

Oxygen,  when  free,  is  a  gaseous  body ;  that  is,  an 
elastic,*  transparent  body  like  air. 

When  oil,  tallow,  charcoal  or  wood  are  burning, 
carbonic  acid  or  fixed  air  is  formed,  by  the  combi- 
nation of  carbon  and  oxygen.  Carbonic  acid  is  the 
gas  that  causes  so  many  accidents  in  caves,  wells, 
&c.  by  people  descending  into  them  without  prop- 
er caution.  Being  heavier  than  air,  it  occupies 
the  lower  portion  of  the  well  or  cave,  and  as  soon  as 
a  person  is  immersed  in  it,  life  is  destroyed.  As  a 
candle  or  lamp  will  not  burn  in  it,  its  presence  can 
be  ascertained  by  lowering  a  candle  into  the  well, 
cave  or  mine.  Should  the  candle  not  burn  freely, 
it  is  not  safe  to  enter. 

Chlorine  and  hydrogen  are  also  gaseous  bodies, 
but  will  not  support  life. 


When  bodies  unite  with  oxygen,  what  generally  happens  ? 
Why  is  it  that  oil,  tallow,  wood,  &c.  burn  when  heated  in 
the  open  air  ?  What  is  oxygen  ?  What  is  a  gas,  or  gaseous 
body  ?  What  gas  is  formed  during  the  burning  of  wood,  oil, 
tallow,  or  charcoal  ?  Is  this  gas  heavier  than  air  ?  Does  it 
ever  cause  accidents,  and  of  what  kind  ?  Will  a  candle  burn 
in  it,  and  how  can  you  ascertain  if  this  gas  exists  in  any 
situation,  and  when  is  it  safe  to  enter  a  well,  cave,  &c.  1  Is 
chlorine  a  gas,  and  will  it  support  life  ? 

*  Bodies  are  said  to  be  elastic  when  they  can  be  compressed  into 
a  smaller  space,  and  when  the  pressure  is  removed,  they  restore  them- 
selves to  their  original  form  and  bulk.  Bodies  that  are  solid  may  be 
bent,  if  longer  than  broad  and  thick.  If  they  restore  themselves  to 
toeir  first  shape  they  are  also  said  to  be  elastic. 


ELEMENTS    OF   GEOLOGY.  51 

Chlorine  is  of  a  yellowish  green  colour,  and  of  a 
peculiar  odour.  It  exists  abundantly  in  combina- 
tion with  sodium  to  form  common  salt.  Salt  is 
contained  in  the  waters  of  the  ocean,  and  in  such 
quantity,  that  if  separated,  it  would  cover  all  the  land 
on  the  globe  to  the  depth  of  1800  feet. 

La  Place  estimated  the  mean  depth  of  the  ocean 
at  10  miles,  and  from  this  and  the  known  quantity 
of  salt  in  the  water,  the  above  estimate  is  made.* 

Hydrogen  gas  is  the  lightest  of  all  known  bodies. 
It  has  no  colour,  burns  with  a  hardly  visible  flame, 
but  gives  a  great  deal  of  heat,  and  when  this  gas  is 
mixed  with  air  or  oxygen,  and  a  flame  applied,  it  ex- 
plodes with  great  violence,  and  water  is  formed. 

It  is  used  for  filling  balloons  by  which  men  are  en- 
abled to  ascend  many  thousands  of  feet  in  the  air. 
If  a  piece  of  cork  be  put  under  water,  it  rises  to  the 
surface,  because  it  is  lighter  than  the  water.  In  the 
same  way,  as  hydrogen  is  so  much  lighter  than  air,  a 
large  bag  filled  with  it,  is  lighter  than  the  air,  and  if 
left  to  itself,  rises  to  a  certain  height  in  the  atmos- 


What  is  its  colour,  and  has  it  any  odour  ?  With  what  does 
it  exist  in  combination  abundantly  7  To  what  depth  would 
the  salt  of  the  ocean  cover  all  the  land  on  the  globe  ?  Of 
what  is  salt  composed,  besides  chlorine  ?  What  is  the  esti- 
mated mean  depth  of  the  ocean  ?  What  is  the  lightest  of  all, 
known  bodies?  Has  hydrogen  any  colour,  and  does  it  give 
any  light  or  heat  during  its  burning  ?  When  mixed  with 
air  or  oxygen  and  inflamed,  what  effect  is  produced,  and  what 
formed  ?  For  what  is  hydrogen  used  ? 

*  This  estimate  has  been  reduced  to  3  miles,  by  more  recent  inves- 
tigations. 


52  ELEMENTS    OF   GEOLOGY. 

phere.  A  balloon  is  a  ball-shaped  bag  filled  with 
hydrogen,  or  with  rarified  air. 

Silicon  is  a  dark  coloured  substance,  burns  under 
certain  circumstances,  and  by  its  union  with  oxygen 
forms  silex,  which  is  a  white  coloured  powder. 
Silex  exists  pure  in  rock  crystal,  and  nearly  pure 
in  many  minerals,  as  flint,  agate,  cornelian,  jasper, 
quartz,  &c. 

Sand  is  almost  entirely  composed  of  silex,  and 
silex  forms  probably  nearly  one  half  of  the  materials 
of  the  crust  of  the  globe. 

Silex,  when  melted  with  potassa  or  soda,  forms 
glass,  and  this  is  one  of  its  most  important  uses. 

Carbon  is  the  principal  substance  in  all  the  kinds 
of  mineral  coal,  and  charcoal,  and  it  exists  in  large 
proportion  in  wood,  oil,  tallow,  and  all  vegetable  and 
animal  substances. 

The  diamond  is  pure  carbon.  Carbon  is  black, 
except  when  crystallized  as  in  the  diamond. 

Carbon  is  naturally  combined  with  hydrogen,  as 
in  bitumens,  oils,  &c.,  with  oxygen  forming  carbonic 
acid,  and  with  iron  forming  plumbago,  or  black  lead, 
steel  and  cast  iron.  Carbon,  and  the  substances 


Why  is  it  that,  a  balloon  filled  with  hydrogen  will  rise  ? 
What  is  the  appearance  of  silicon,  and  by  its  union  with 
oxygen,  what  is  formed  ?  In  what  does  silex  exist  pure,  and 
in  what  nearly  pure  ?  Of  what  is  sand  mostly  composed  ? 
What  proportion  of  the  crust  of  the  Earth  is  silex?  What 
is  silex  mostly  used  for,  and  how  is  glass  made  ?  In  what 
is  carbon  the  principal  substance,  and  in  what  does  it  exist  in 
large  proportions?  What  substance  is  pure  carbon?  In 
what  is  carbon  naturally  combined  with  hydrogen  ?  What 
are  formed  by  the  union  of  carbon  and  iron  ? 


ELEMENTS   OP  GEOLOGY.  53 

containing  it  in  large  proportion,  are  mostly  used 
for  obtaining  light  and  heat,  and  for  reducing  the 
ores  of  the  metals. 

Sulphur  is  a  simple  body  of  yellow  colour,  brittle, 
without  taste,  burns  easily  in  the  open  air,  ancT  gives 
a  peculiar  pungent  odour.  It  rarely  occurs  uncom- 
bined  with  other  bodies,  except  in  volcanic  coun- 
tries. It  is  found  united  to  many  of  the  metals  form- 
ing  ores,  which  are  called  sulphurets.  It  is  used 
mostly  for  the  manufacture  of  gunpowder,  and  sul- 
phuric acid,  or  oil  of  vitriol. 

Iron,  combined  with  oxygen,  forms  most  of  the 
useful  ores  of  iron,  but  there  are  few  places  compar- 
atively, where  these  ores  are  found  in  such  quan- 
tity as  to  be  valuable. 

This  combination  is  more  uniformly  distributed 
through  the  mineral  kingdom  than  any  other  sub- 
stance, and  it  colours  almost  all  minerals.  Hardly 
a  fragment  of  mineral  or  rock  can  be  selected,  that 
does  not  contain  traces  of  iron,  but  generally  it  is 
in  small  quantity. 

Oxides  are  combinations  of  oxygen  with  other 
bodies.  The  oxides,  silex,  alumina,  lime,  and  mag- 
nesia, are  called  earths,  and  the  two  last,  alkaline 


For  what  are  carbon,  and  substances  containing  it  in  large 
proportions,  employed  ?  What  are  some  of  the  properties  of 
sulphur  ?  Does  it  occur  uncombined  with  other  bodies,  anfl 
where  ?  When  united  with  the  metals,  what  are  formed, 
and  what  are  they  called  ?  For  what  is  sulphur  mostly  em. 
ployed  ?  Of  what  are  most  of  the  useful  ores  of  iron  com. 
posed  ?  Are  these  found  in  quantity  every  where  ?  Is  iron 
almost  universally  distributed  in  the  mineral  kingdom? 
Does  it  generally  colour  minerals  ?  What  are  oxides  ?  What 
are  the  most  abundant  earthy  oxides  ? 
5* 


54  ELEMENTS    OF   GEOLOGY. 

earths.  These  earths  are  most  abundant  in  the 
same  order  in  which  they  are  mentioned,  and  they 
constitute  at  least  three  fourths  of  the  solid  mate- 
rials upon  the  surface  of  the  globe. 

These  substances,  by  their  various  combinations 
with  each  other,  and  with  other  bodies,  form  a  great 
variety  of  minerals,  and  it  is  not  a  little  remarkable, 
that  those  minerals  and  substances  most  useful  to 
man,  are  most  abundant  and  most  uniformly  dis- 
tributed. 

There  are  about  forty-five  simple  bodies  known, 
in  addition  to  those  already  described ;  and  although 
they  form  a  small  portion  of  the  mass  of  the  globe, 
in  comparison  with  those  previously  noticed,  some 
of  them  are  highly  useful,  and  almost  indispensable, 
to  man  in  his  civilized  state. 

They  are : 

BROMINE  ;  CHROMIUM  ; 

IODINE  ;  URANIUM  ; 

FLUORINE  ;  VANADIUM  ; 

NITROGEN  ;  MOLYBDENUM  ; 

BORON  ;  TUNGSTEN  ; 

PHOSPHORUS  ;  TITANIUM  ; 

SELENIUM  ;  COLUMBIUM 

ARSENIC  ;  LITHIUM  ; 

ANTIMONY  ;  MAGNESIUM  ; 

TELLURIUM  ;  STRONTIUM  ; 

Which  is  most  abundant  ?  What  proportion  of  the  solid 
materials  of  the  globe  do  they  form  ?  When  these  substances 
combine  with  each  other  and  other  bodies,  do  they  form  many 
minerals  ?  Are  the  most  useful  minerals  the  most  abundant 
and  widely  distributed  ?  How  many  simple  bodies  known  in 
addition  to  those  already  given  ?  Name  them  ? 


ELEMENTS   OF   GEOLOGY.  55 

BARIUM  ;  TIN  ; 

GLUCINIUM  ;  BISMUTH  ; 

YTTRIUM  ;  COPPER  ; 

ZIRCONIUM  ;  MERCURY  ; 

THORIUM  ;  SILVER  ; 

MANGANESE  ;  GOLD  ; 

NICKEL  ;  PLATINUM  ; 

COBALT  ;  PALLADIUM  ; 

CERIUM  ;  RHODIUM  ; 

ZINC  ;  IRIDIUM 

CADMIUM  ;  OSMIUM. 

LEAD  ; 

"  Bromine  and  Iodine  are  both  found  in  combi- 
nation with  other  bodies,  most  frequently  in  sea 
water,  and  in  small  quantities. 

"  Iodine  is  the  most  important  of  the  two.  It 
forms  several  compounds,  and  is  useful  in  medicine 
and  the  arts. 

"  Fluorine  is  a  principle  found  to  exist  in  the  min- 
eral called  fluorspar.  It  has  not  yet  been  obtained 
in  a  perfectly  pure  state.  The  fluoric  acid  gaslnto 
the  composition  of  which  the  fluorine  enters,  is  re- 
markable for  its  property  of  corroding  glass. 

"Nitrogen  constitutes  four-fifths  of  atmospheric 
air,  and  is  an  ingredient  of  animal  substances. 
This  element  is  remarkable  for  its  negative  quali- 
ties; it  is  neither  combustible  nor  a  supporter  ^of 
combustion ;  neither  acid  nor  alkaline.  No  ahi- 
mal  can  exist  in  it ;  not  because  it  has  any  injuri- 


What  of  the  two  first  ?  Which  is  the  most  useful  ?  What 
of  Fluori  MC  ?  What  corrodes  glass  ?  What  portion  of  atmos- 
pheric air  does  Nitrogen  constitute  ?  £fume  the  qualities  for 
which  it  i£  remarkable  1 


56  ELEMENTS   OF   GEOLOGY. 

ous  effect  upon  the  lungs,  but  solely  from  the  ab- 
sence of  oxygen. 

"  Nitrogen,  however,  when  it  combines  with  other 
substances,  forms  compounds  which  are  not  distin- 
guished by  negative  qualities,  but  are  highly  impor- 
tant in  the  arts  and  medicine. 

"  Boron  is  a  dark  olive-coloured  powder,  and  is 
the  base  of  borax,  a  substance  found  in  the  East  In- 
dies and  in  the  lakes  of  Thibet  and  China.  It  has 
no  taste  and  is  insoluble  in  water. 

"Phosphorus  is  never  found  in  nature  uncom- 
bined.  Nor  can  it  exist  in  this  state,  for  it  is  ex- 
ceedingly combustible  ;  and  (according  to  Dr.  Hig- 
gins,)  burns  at  a  temperature  of  60°  Fahrenheit,  in 
atmospheric  air.  It  combines  with  nearly  all  the 
metals,  the  earths,  and  the  principles  already  de- 
scribed. 

"  Selenium  was  discovered  by  Berselius,  but  its 
quantity  in  nature  is  so  small,  that  it  is  difficult  to 
say  what  purpose  it  can  have  to  accomplish.  It  is 
usually  combined  with  sulphur. 

"  Selenium  forms  two  acids  with  oxygen.  It  also 
forms  a  deleterious  gaseous  compound,  hydroselenic 
acid  with  hydrogen. 

"Arsenic  sometimes  occurs  native, but  it  is  usually 
in  combination  with  cobalt  or  iron.  The  white 
arsenic  of  commerce  is  not  the  pure  metal,  but  con- 
tains oxygen,  and  is  the  arsenious  acid.  This  and 

When  combined  with  other  substances  what  does  it  form  ? 
What  of  Boron  ?  How  is  Phosphorus  always  found  ?  Why  ? 
Who  discovered  Selenium  ?  What  does  it  form  with  Oxy- 
gen ?  What  with  Hydrogen  ?  In  what  state  is  Arsenic 
found  ?  What  of  the  white  Arsenic  of  commerce  ? 


ELEMENTS    OF   GEOLOGY.  57 

arsenic  acid,  are  known  for  their  extremely  poison- 
ous  qualities. 

"  Pure  metallic  arsenic  has  a  bright  bluish-white 
colour,  a  crystalline  texture,  and  is  very  brittle. 
When  cold,  it  has  no  smell ;  but  its  vapour  has  the 
odour  of  garlic,  by  which  the  metal  may  be  always 
distinguished. 

"Antimony  was  discovered  by  Basil  Valentine 
in  the  fifteenth  century,  and  is  said  to  have  received 
its  name  from  the  circumstance  that  several  monks 
were  killed  by  taking  it  as  a  medicine.  It  is  some- 
times found  native,  but  more  frequently  as  a  sul- 
phuret.  The  metal  has  a  bluish-white  colour,  con- 
siderable brillancy  and  is  very  brittle.  The  oxides 
of  antimony  are  used  in  medicine. 

"Tellurium,  Chromium,  Uranium,  Vanadium, 
Molybdenum,  Tungsten,  Titanium,  and  Columbium, 
are  not  abundant  in  nature  ;  and  excepting  chro- 
mium, which  is  sometimes  used  in  the  preparation 
of  colours,  are  useless  in  the  arts.  The  mere  men- 
tion of  their  names  will  therefore  be  sufficient. 

"  Lithium  is  the  metallic  base  of  Lithia,  a  sub- 
stance found  in  a  mineral  called  petalite  by  M. 
Arfwedsen,  and  since  found  in  spodumere,  lepidolite. 

"  Lithium  is  a  white-coloured  metal,  and  has  a 
great  affinity  for  oxygen. 

"  We  are  indebted  to  Davy  for  the  knowledge  of 
lithium,  potassium,  and  sodium,  all  of  which  were 

What  distinguishes  the  pure  metallic  Arsenic  ?  By  whom 
was  Antimony  discovered  ?  By  what  circumstance  did  it 
receive  its  name  ?  Name  those  bodies  that  are  useless  in  the 
arts?  Who  discovered  Lithium?  To  whom  are  we  in- 
debted for  the  knowledge  of  it  ? 


58  ELEMENTS    OF    GEOLOGY. 

detecte    by  the  application  of  voltaic  electricity  to 
their  several  oxides. 

"  Strontium  the  base  of  strontian,  is  a  heavy  me- 
tal ;  and  not  abundant  in  nature. 

"  Barium  is  a  dark  gray-coloured  metal  that  has 
a  strong  attraction  for  oxygen,  and  is  the  base  of 
barytes. 

"  Glucinium,  Yttrium,  Zirconium,  and  Thorium, 
are  metallic  principles  discovered  by  the  analysis  of 
some  rare  minerals.  They  appear  to  exist  in  very 
small  quantities  ;  and  it  is  therefore  only  necessary 
that  their  names  should  be  mentioned. 

"  Manganese  is  never  found  in  a  metallic  state ; 
for  it  has  so  great  an  affinity  for  oxygen,  that  it  is 
oxydised  by  mere  exposure  to  the  air.  It  was  first 
procured  in  a  metallic  form  by  Gahn  in  the  year 
1775.  Manganese  is  a  bright  metal,  of  a  darkish- 
white  colour,  brittle,  but  hard. 

"  Nickel  is  a  white  ductile  malleable  metal.  Its 
principal  ore  is  a  copper-coloured  mineral,  called 
Kupfer,  or  copper  nickel,  which  is  an  arseniuret. 
It  is  not  abundant  as  a  mineral,  but  is  found  in 
nearly  all  meteoric  stones. 

"  Cobalt  is  a  grayish-coloured  metal,  brittle,  and 
difficult  of  fusion.  Both  cobalt  and  nickel  obey  the 
magnetic  force.  The  ores  of  cobalt  are  procured  from 
Sweden,  Saxony,  and  from  some  parts  of  England. 


How  was  it  detected  ?  What  of  Strontium  ?  What  of 
Barium  ?  What  bodies  were  discovered  by  the  analysis  of 
some  rare  metals  ?  Why  is  Manganese  not  found  in  a  me- 
tallic  state  ?  By  whom  was  it  first  procured  ?  What  of 
Nickel  ?  Where  are  the  ores  of  Cobalt  procured  ?  What 
attractive  force  do  Cobalt  and  Nickel  obey  ? 


ELEMENTS    OF    GEOLOGY.  59 

"  Cerium  was  discovered  in  the  year  1804,  but  its 
properties  are  not  known  ;  and  it  has  been  obtained 
only  in  very  small  quantities. 

"  Zinc  is  one  of  the  most  combustible  of  all  the 
metals,  has  a  bluish-white  colour,  laminated  texture, 
and  great  fusibility.  Calamine,  a  native  carbonate ; 
and  Blende,  a  native  sulphuret ;  are  its  most  im- 
portant ores. 

"  Cadmium  is  a  soft,  ductile  metal,  usually  found 
in  combination  with  zinc.  It  was  discovered  in  an 
oxide  of  zinc,  in  the  year  1817,  by  Strome,yer. 

"  Lead  is  chiefly  obtained  from  a  mineral  called 
galena^  which  consists  of  lead  and  sulphur.  The 
ores  of  this  well  known  metal  are  very  abundant, 
and  the  metal  itself  is  extensively  employed  in  the 
arts. 

"  Tin  was  known  to  the  ancients.  Cornwall  has 
been  long  celebrated  for  its  production.  It  chiefly 
occurs  as  an  oxide  among  the  primitive  rocks.  Tin 
is  a  white,  malleable  metal,  and  is  extensively  used 
in  the  arts,  and  in  the  manufacture  of  metallic  goods. 

"  Bismuth  is  a  reddish-white  laminated  metal,  and 
is  found  native,  as  well  as  in  combination  with  other 
substances. 

"  Copper  is  one  of  the  most  abundant  of  the  me- 
tals, and  is  chiefly  obtained  from  the  native  sul- 
phuret though  it  is  also  found  in  its  metallic  state. 


When  was  Cerium  discovered  ?  What  peculiar  property 
distinguishes  Zinc?  What  are  its  most  important  ores? 
When  and  by  whom  was  Cadmium  discovered  ?  From  what 
is  Lead  chiefly  obtained  ?  Where  does  Tin  mostly  occur  as 
an  oxide  ?  For  what  has  Cornwall  been  long  celebrated  ? 
What  of  Bismuth  ?  What  distinguishes  Copper  ? 


60  ELEMENTS    OF    GEOLOGY. 

It  may  be  distinguished  from  all  other  metals,  ex- 
cept titanium  by  its  red  colour.* 

"  Mercury,  or  quicksilver,  is  the  only  metal  that 
is  fluid  at  common  temperatures.  It  is  found  in 
various  states,  both  native  and  in  combination, 
chiefly  with  sulphur. 

"  Mercury  freezes  at  thirty-nine  degrees  below 
zero  of  Fahrenheit's  scale,  and  in  Hudson's  Bay  it 
was  not  only  solidified,  but  beaten  into  sheets  as 
thin  as  writing  paper.  The  mercury  of  commerce 
is  chiefly  obtained  from  Spain  and  Peru. 

"  Silver  is  found  native,  and  in  combination  with 
sulphur  and  several  of  the  metals.  Although  the 
metal  has  a  great  commercial  value,  yet  as  an  in- 
gredient  in  the  composition  of  the  earth's  crust,  it 
is  very  unimportant. 

"  Silver  has  however  many  properties  such  as 
malleability,  ductility,  and  tenacity,  which  would 
make  it  valuable  in  the  arts,  if  it  could  be  obtained 
for  such  purposes. 

"  Gold  has  always  been  found  in  a  metallic  state, 
either  pure  or  in  combination  with  some  other  me- 
tal. Gold  is  chiefly  obtained  from  Africa  and  South 
America,  but  in  so  small  quantities,  that  it  must  be 
considered  as  an  unimportant  mineral  principle,  f 


How  is  Mercury  usually  found  ?  At  what  degree  does  it 
freeze  ?  What  is  said  of  it  in  Hudson's  Bay  ?  What  is  said 
of  Silver  ?  What  properties  has  Silver  ?  In  what  state  has 
Gold  been  always  found  ? 

*  Copper  may  be  distinguished    from   Titanium    by   its  softness. 

t  It  is  found  in  the  United  States  in  larger  masses  and  more  exten- 
sively diffused  than  in  any  other  Country.  Masses  of  more  than 
201b.  weight  hare  been  found  in  North  Carolina. 


ELEMENTS    OF    GEOLOGY.  61 

"Platinum  is  the  heaviest  of  all  metals,  has  a 
brilliant  white  colour  and  is  very  ductile.  It  is 
found  in  many  parts  of  South  America,  and  usually 
in  grains.  The  largest  mass  ever  found,  now  in  the 
Royal  Museum  at  Madrid,  does  not  weigh  more 
than  a  pound  and  three  quarters. 

"  Palladium,  Rhodium,  Iridium,  and  Osmium,  are 
also  obtained  in  very  small  quantities,  and  together 
form  so  inconsiderable  a  portion  of  the  earth's  crust, 
that  we  need  not  take  any  farther  notice  of  them. 

"  In  the  vast  laboratory  of  the  earth,  these  prin- 
ciples have  been  at  various  times  so  submitted  to 
each  other,  as  to  produce  the  compounds  which  are 
now  found  in  large  masses,  constituting  rocks,  and 
in  smaller  portions  as  mineral  specimens. 

"  But  all  these  compounds  have  been  formed  in 
obedience  to  the  same  general  laws  as  now  influence 
the  union  of  particles  and  masses,  and  it  is  upon  our 
knowledge  of  these  laws,  that  we  must  depend  for 
an  explanation  of  the  many  difficulties  that  are  felt 
in  accounting  for  the  present  state  of  mineral  com- 
pounds."* 

What  qualities  has  Platinium  ?  What  is  the  weight  of  the 
largest  mass  of  it  ever  found  ?  Name  those  bodies  that  form 
so  inconsiderable  a  portion  of  the  earth's  crust  ?  On  what 
are  we  to  depend  for  our  knowledge  of  general  laws  ? 

*  Higgins  on  the  earth,  pp  371.  377.  , 

6 


62  QUARTZ. 


CHAPTER  III. 


It  has  been  remarked  that  notwithstanding  the 
variety  of  minerals,  those  forming  the  mass  of  the 
globe,  as  far  as  exposed  to  our  observation,  are  few 
in  number,  viz : 

1  QUARTZ  ;  6  CHLORITE  ; 

2  FELDSPAR  ;  7  TALC  ; 

3  MICA  ;  8  GYPSUM  ; 

4  HORNBLENDE  ;  9  LIMESTONE  ; 

5  AUGITE  ;  10  SERPENTINE. 

Slate  and  clay  might  be  added,  but  they  are  rather 
aggregated  minerals,  in  a  minute  state  of  division, 
than  distinct  minerals. 

QUARTZ. 

Quartz  consists  entirely  of  silex.  Rock  crystal, 
which  is  clear  transparent  quartz,  is  pure  silex. 
Quartz  varies  much  in  its  colour,  but  is  most  gene- 
rally white  or  light  coloured.  It  is  hard — scratches 
glass — cannot  be  cut  with  a  knife — strikes  fire  with 
steel — cannot  be  easily  melted  alone — and  when  two 
pieces  are  rubbed  together  in  the  dark  they  give  out 
light,  or  phosphoresce,  as  it  is  termed,  and  a  pecu- 
liar odour  is  emitted.  Quartz,  when  broken,  has  a 


What  are  the  minerals  of  the  geological  alphabet  ?    What 
substances  might  be  added  ?     Of  what  is  quartz  composed  ? 
;  What  mineral  is  pure  silex?    What  are  the  properties  of 
;  quartz? 


FELDSPAR.  63 

lustre  upon  the  surface  like  broken  glass,  but  when 
the  quartz  is  not  clear  or  transparent,  the  lustre  is 
greasy  or  looks  like  a  bright  surface  over  which  oil 
had  been  rubbed. 

Quartz  is  generally  in  rough,  shapeless  masses ; 
but  sometimes  is  in  beautifully  regular  forms,  more 
brilliant,  and  perfect  in  form,  than  the  Lapidary 
could  make  them. 

These  regularly  formed  bodies,  whether  they 
be  quartz,  or  any  other  mineral,  or  any  sub- 
|  stance  whatever,  are  called  crystals.     The 
usual  form  under  which  quartz  crystallizes, 
is  a  six-sided  prism  terminated  by  six-sided 
pyramids,  as  seen  in  the  margin. 

Quartz  occurs  compact  or  solid,  when  it  is  said 
to  be  massive ;  and  granular,  when ,  composed  of 
grains  like  some  of  the  sandstones.  When  quartz 
is  very  porous  it  is  said  to  be  spongiform  ;  when  in 
pendulous  masses  like  a  stalactite  or  icicle,  it  is 
stalactical  quartz. 

Quartz  sometimes  forms  whole  mountains,  but 
more  often  it  is  in  aggregated  masses  with  other 
minerals,  to  form  rocks.  Quartz  occurs  abundantly 
on  the  sea  shore,  and  in  the  interior  of  almost  every 
country,  in  the  form  of  sand.  The  white  pebbles 


In  what  form  is  quartz  generally  observed  ?  What  are 
crystals  ?  and  what  is  the  form  in  which  quartz  crystallizes  ? 
What  is  massive  quartz  ?  What  granular  quartz  ?  What 
spongiform  quartz  ?  and  stalactic  quartz  ?.  Does  quartz  ever 
form  mountain  masses  ?  In  what  situation  is  it  more  fre- 
quently found  ?  What  is  sand  ?  What  are  the  white  peb- 
bles in  gravel"? 


64  MICA. 

in  gravel  are  quartz,  as  are  most  of  the  hard  stones 
that  we  see  about  the  country. 

FELDSPAR. 

There  are  several  varieties  of  Feldspar,  but  they 
agree  in  some  of  their  more  important  characters. 
They  are  composed  of  the  same  ingredients,  viz  : 
silica,  alumina,  and  potassa.  They  are  all  hard 
enough  to  scratch  glass,  but  are  less  hard  than 
quartz.  Feldspar  is  laminar,  or  composed  of  plates, 
and  it  has  a  shining  lustre.  Its  colour  is  variable, 
but  is  generally  white  or  reddish.  It  can  be  melted 
without  difficulty. 

It  is  sometimes  crystallized,  and  almost  always 
crystalline ;  and  the  brilliant  surfaces 
when  it  is  broken,  are  in  the  direc- 
tions of  the  faces  of  the  figure  in  the 
margin,  the  faces  P  and  M  being  per- 
pendicular  to  each  other,  the  others 
oblique. 

Feldspar  is  sometimes  compact,  and  sometimes 
forms  mountain  masses,  but  more  frequently  it  forms 
a  constituent  part  of  other  rocks,  as  granite,  sienite, 
&c.  Feldspar  is  used  in  the  manufacture  of  por- 
celain or  china  ware  as  it  is  called. 

MICA. 

Mica  is  composed  of  the  same  substances  essen- 


Of  what  is  feldspar  composed  ?  What  are  the  properties 
of  feldspar  ?  Is  feldspar  always  crystalline  ?  Does  it  ever 
form  mountains,  and  where  is  it  more  commonly  found,  and 
in  what  rocks  ?  For  what  is  feldspar  employed  ?  Of  what 
is  mica  composed  ? 


HORNBLENDE.  65 

tially  as  Feldspar,  but  in  different  proportions. 
Mica,  or  isinglass  as  it  is  sometimes  called,  is  found 
imbedded  in  rocks  either  in  small  scales,  or  some- 
times in  masses  of  some  magnitude.  It  very  easily 
splits  into  thin  layers  or  leaves,  which  are  transpa- 
rent, flexible  and  elastic.  Mica  is  sometimes  called 
Muscovy  glass,  because  in  Russia  it  is  often  used 
instead  of  glass  for  windows.  It  occurs  of  all  shades 
of  colour^from  white  to  black.  The  surface  of  the 
plates  of  mica  has  a  strong  shining  lustre  ;  and  it 
in  fact  derives  its  name  from  the  Latin,  micans, 
signifying  glittering.  It  melts  without  difficulty. 
It  is  found  in  greater  or  less  quantity  in  a  large 
proportion  of  the  rocks.  Its  elasticity,  and  the 
strength  of  its  thin  plates,  renders  it  superior  to 
glass  for  many  uses.  It  can  be  scratched  by  a 
knife,  but  is  scarcely  hard  enough  to  scratch  glass. 

HORNBLENDE. 

Hornblende  is  composed  of  silex,  alumina,  lime, 
magnesia,  and  oxide  of  iron.  It  is  generally  of  a 
dark  green  colour,  and  between  that  and  black.  It 
is  heavier  than  quartz  or  feldspar,  but  not  so  hard, 
and  is  much  more  difficultly  broken.  It  derives  a 
part  of  its  name  from  its  being  tough,  and  difficult 
to  break,  like  horn.  It  can  be  scratched  witli  a 
knife,  and  its  powder  is  of  a  light  green  colour. 


What  is  a  common  name  for  mica,  and  where  is  it  found  ? 

What  are  the  properties  of  mica?      For  what  is  mica 
sometimes  used,  and  why  ?     Is  mica  found  in  many  of  the 
rocks  ?     Of  what  is  hornblende  composed  ?     What  are  its 
properties  ?     From  what  does  it  derive  its  name  ? 
6* 


66  HORNBLENDE AUGITE. 

When  breathed  upon  it  gives  an  odour  like  that  of 
moist  clay,  which  is  called  the  argillaceous  odour. 
It  melts  easily,  and  boils  up  or  intumesces  when 
melted.  It  often  occurs  crys- 
tallized, as  seen  in  the  margin, 
but  is  far  more  common  in  rude, 
shapeless  masses.  IF  however 
these  masses  be  examined  closely,  minute  crystals, 
having  the  first  of  these  forms,  may  be  observed. 

Hornblende  is  sometimes  in  granular  masses,  or 
else  composed  of  long  needle-shaped,  or  acicular 
crystals,  and  sometimes  these  long  crystals  diverge 
from  a  centre,  and  are  stellar  or  star-shaped,  or  ra- 
diated like  the  spokes  of  a  wheel,  and  the  lustre  is 
either  shining,  or  silky.  Common  hornblende  some- 
times forms  entire  mountains  by  itself,  but  it  is  more 
frequently  aggregated  with  other  minerals  to  form 
rocks,  as  sienite,  greenstone,  &c. 

AUGITE. 

Augite  is  composed  principally  of  silica,  lime  and 
magnesia.  It  is  generally  black  or  green,  but  some- 
times light  coloured.  It  often  resembles 
hornblende,  but  it  is  much  harder,  arid  will 
strike  fire  with  steel ;  and  it  does  not  melt 
so  easily.  It  is  often  crystallized  in  4  or 
8  sided  prisms.  Augite  is  found  abun- 

Does  it  occur  crystallized  ?  Under  what  other  forms  does 
it  occur?  Does  hornblende  ever  form  extensive  masses? 
In  what  rocks  is  it  contained  as  a  part  of  the  rock  ?  Of 
what  is  augite  composed  ?  What  are  its  properties  ?  Does 
it  ever  occur  crystallized  ?  In  what  rocks  is  it  found  ? 


CHLORITE TALC.  67 

dantly  in  rocks  of  volcanic  origin,  and  in  some  of 
the  rooks  called  trap-rocks,  and  which  are  by  many 
thought  to  be  of  volcanic  origin.  It  is  also  found 
in  primitive  rocks.  It  occurs  massive,  or  without 
any  regular  form ;  and  granular,  and  then  it  is  called 
coccolite. 

CHLORITE. 

Chlorite  is  composed  principally  of  silica,  alumina, 
magnesia,  and  oxide  of  iron.  It  is  of  a  green  colour, 
usually  a  dark  green,  and  derives  its  name  from  a 
Greek  word  signifying  green.  It  is  in  general  an 
aggregation  of  small  green  scales  ;  is  so  soft  that  it 
can  be  scratched  by  the  finger  nail,  and  feels  soft 
and  smooth,  or  unctuous  when  rubbed  between  the 
fingers.  It  is  much  softer  than  mica,  and  the  lat- 
ter does  not  feel  greasy  or  soapy  between  the  fingers. 

TALC. 

Talc  is  composed  principally  of  silex  and  mag- 
nesia.  It  has  many  of  the  properties  of  chlorite, 
but  it  has  various  colours,  and  is  rarely  of  a  dark 
green  like  chlorite.  It  feels  more  unctuous  and 
soapy  between  the  fingers  than  chlorite.  Talc  \s 
distinguished  from  mica,  by  its  plates  being  flexible, 


When  it  is  granular,  what  is  it  called  ?  Of  what  is  chlo- 
rite composed  ?  What  are  its  characters  ?  How  is  it  dis- 
tinguished from  mica  ?  Of  what  is  talc  composed  ?  How 
does  it  differ  from  chlorite  ?  How  do  talc  and  chlorite  feel 
between  the  fingers  ?  Which  is.  most  unctuous  ?  How  is 
talc  distinguished  from  mica  ? 


68  GYPSUM. 

but  not  elastic  like  mica.  Talc  is  generally  softer 
than  chlorite,  and  is  easily  scratched  with  the  finger 
nail.  It  does  not  easily  melt,  but  chlorite  does. 
Both  talc  and  chlorite  enter  into  the  composition  of 
rocks,  and  the  rocks  are  said  to  be  talcous  or  chlo- 
ritic. 

GYPSUM. 

Gypsum  is  composed  of  sulphuric  acid  or  oil  of 
vitriol,  united  with  lime.  The  common  gypsurn 
also  contains  water  united  to  the  above  mentioned 
substances.  Gypsum  is  generally  white,  but  some- 
times  gray,  red,  and  of  various  colours.  It  is  often 
compact,  but  sometimes  granular  and  crystallized. 
When  crystallized,  it  is  frequently  in 
transparent  plates,  having  4  sides,  and 
can  be  separated  into  thin  plates  like 
mica  and  talc.  If  heated,  it  does  not 
melt  easily,  but  loses  about  one-fifth  of  its  weight, 
and  if  transparent,  it  becomes  white  and  opake.* 
It  is  used  for  a  great  variety  of  purposes,  the  most 
important  of  which,  are,  for  a  manure,  for  cements, 
and  for  castings.  It  sometimes  forms  hills,  but 
more  often  it  forms  layers  or  beds  in  other  rocks, 
and  is  generally  connected  with  salt  springs  or  rock 
salt. 


Of  what  is  gypsum  composed  ?  What  does  gypsum  con- 
tain  besides  sulphuric  acid  and  lime  ?  What  are  the  proper* 
ties  of  gypsum  ?  When  gypsum  is  heated,  what  are  the 
effects  ?  For  what  is  gypsum  used  ?  With  what  is  gypsum 
generally  connected  ? 

*  A  body  is  opake  when  the  light  cannot  be  seen  through  it. 


LIMESTONE.  69 

LIMESTONE. 

Limestone  is  composed  of  carbonic  acid  united 
or  combined  with  lime,  and  is  called  carbonate  of 
lime ;  gypsum  is  called  sulphate  of  lime.  Lime- 
stone  or  carbonate  of  lime  varies  more  in  its  ap- 
pearance than  any  other  mineral.  It  occurs  of  all 
colours,  and  varies  from  a  coarse  grained,  to  the 
most  compact  marbles ;  from  a  rough  un- 
seemly stone,  to  a  fine  earthy  powder ; 
and  not  unfrequently  it  is  found  in  the 
most  beautiful  crystals.  The  crystals 
occur  under  more  than  seven  hundred  different 
forms,  but  by  splitting  them,  the  same  form,  or  primi- 
tive form,  is  obtained  from  all  of  them.  The  primi- 
tive form  is  a  rhomboid,  a  solid,  having  all  its  faces 
equal  to  each  other,  but  the  angles  not  right  angles. 
The  crystallized  transparent  carbonate  of  lime  is 
called  calcareous  spar,  and  has  some  remarkable 
qualities.  If  a  rhombic  crystal  of  calcareous  spar 
be  placed  on  a  piece  of  paper,  with  a  fine  line  of  ink 
drawn  upon  it  that  may  be  distinctly  seen  through 
the  crystal,  the  line  appears  double,  or  there  appear 
to  be  two  lines  near  together.  If  the  crystal  be 
turned  around  gradually,  the  lines  approach  each 
other  until  only  one  is  visible,  and  by  turning  it  still 


Of  what  is  Jimestone  composed  ?  By  what  other  names 
are  limestone  and  gypsum  called?  Does  limestone  vary 
much  in  its  appearance  ?  What  are  some  of  the  various 
appearances  and  textures  it  presents?  Does  carbonate  of 
lime  occur  crystallized?  Has  it  many  crystalline  forms? 
Can  they  all  be  reduced  to  one?  What  is  the  primitive 
*brm  ?  What  remarkable  properties  are  observed  in  calca- 
•xms  spar  ? 


70  LIMESTONE. 

farther  they  again  appear,  and  recede  from  each 
other  until  you  have  turned  it  half  round,  after  which 
they  again  approach  until  only  one  line  appears. 
This  is  called  double  refraction.*  Calcareous  spar 
becomes  electrified")*  by  rubbing  it,  and  even  by  pres- 
sing it  between  the  fingers,  and  retains  its  elec- 
tricity for  some  time.  „ 

Notwithstanding  the  great  variety  of  appear- 
ranees  presented  by  carbonate  of  lime,  it  may  be 
easily  recognized  by  the  following  characters.  Car. 
bonate  of  lime  can  be  scratched  with  a  knife — acids 
when  poured  on  it  boil  up  or  effervesce  violently — 
and  when  heated  highly,  it  becomes  quicklime,  in 
which  state  it  is  easily  recognized  by  the  taste,  and 
by  its  burning  the  tongue.  If  a  large  fragment  of 
it  have  water  thrown  upon  it,  it  becomes  hot  and 
crambles  to  a  white  powder. 

Limestone  occurs  abundantly  in  every  country  ; 
it  forms  mountains,  and  even  ranges  of  mountains. 
The  strong  granular  and  compact  limestones  are  used 
as  marbles ;  many  of  them  make  good  building 
stones,  and  lime ;  chalk  is  used  for  marking,  and  mak- 
ing lime  and  whiting,  and  marl  is  used  as  a  manure. 


How  may  carbonate  of  lime  be  recognized  ?  Does  lime- 
stone occur  abundantly  ?  For  what  are  the  various  kinds  ot 
carbonate  of  lime  employed  ? 

*  Light  is  said  to  be  refracted  when,  in  passing  through  a  transparent 
body,  it  is  bent  out  of  its  course.  A  stick,  when  put  into  water,  ap- 
pears bent,  and  to  have  a  different  direction  in  the  water  from  what  it 
has  out.  This  is  owing  to  refraction. 

t  Electrified  bodies  attract  light  substances  :  and  if  the  electrified 
surface  be  of  any  considerable  magnitude,  on  approaching  it  to  any 
part  of  the  body,  a  small  spark  is  seen,  and  a  snapping  noise  heard. 
The  spark  is  similar  to  lightning,  and  the  noise  to  thunder,  only  infi- 
nitely smaller. 


SERPENTINE SLATE  AND  CLAY.  71 

SERPENTINE. 

Serpentine  is  composed  of  silica,  magnesia,  and 
water,  but  sometimes  contains  a  small  proportion 
of  other  substances,  as  alumina,  oxide  of  iron,  dec. 
Its  colour  is  generally  some  tint  of  green,  but  often 
variegated.  Serpentine  derives  its  name  from  the 
colours  being  variegated  somewhat  like  the  skin  of  a 
serpent.  It  is  generally  compact — rarely  granular 
or  crystalline — yields  to  the  knife — is  somewhat 
unctuous  to  the  touch— and  is  capable  of  receiving 
a  high  polish.  It  is  sometimes  used  as  a  marble,  and 
limestone  sometimes  contains  serpentine  dissemi- 
nated through  it  in  grains,  and  is  then  called  verd 
antique  marble.  Serpentine  forms  considerable 
masses  in  many  parts  of  the  world,  and  it  seems  to 
be  the  repository  of  the  chrome  iron,  used  so  exten- 
sively to  obtain  chromate  of  lead  or  chrome  yellow. 

SLATE  AND  CLAY. 

s 

These  substances  are  mostly  composed  of  silica 
and  alumina,  and  sometimes  a  little  carbon  or  oxide 
of  iron.  Most  of  the  slates  can  be  scratched  easily 
by  the  knife,  and  the  clays  by  the  finger  nail.  The 
slates  generally  split  out  into  thin  layers,  and  some 
of  the  clays  do  the  same.  When  broken,  they  both 
show  a  fine  grained  fracture,  and  the  clay,  parti* 

Of  what  is  serpentine  composed  ?  What  is  its  colour  ? 
What  are  its  properties  ?  For  what  is  it  employed  ?  What 
is  verd  antique  marble  ?  Does  serpentine  form  large  masses  ? 
What  mineral  is  found  in  serpentine,  and  for  what  is  it  em- 
ployed ?  Of  what  are  slates  and  clays  composed  ?  What 
are  their  characters  ? 


72  STRATIFICATION. 

cularly,  shows  what  is  called  the  earthy  fracture. 
Both  slates  and  clays  give  the  argillaceous  odour 
when  breathed  upon. 

Slate  is  used  for  drawing  slates  and  for  pencils, 
for  roofing  buildings,  &c.,  and  the  clays  are  em- 
ployed for  making  bricks,  and  various  kinds  of  pot- 
tery. 

Slate  often  forms  extensive  masses,  and  clay  ge- 
nerally occurs  in  detached  beds,  often  of  consider- 
able extent. 


CHAPTER  IV. 
STRATIFICATION. 

Knowing  the  elementary  and  mineral  bodies  of 
which  the  globe  is  composed,  we  find,  by  observa- 
tion, that  the  aggregated  masses  of  these  substances, 
or  rocks,  are  arranged  in  a  regular  order  of  super- 
position with  regard  to  each  other.  For  instance, 
rocks,  containing  coal,  in  one  country,  lie  below 
those  containing  salt.  In  other  countries,  the  same 
rocks  may  be  expected  to  occur  in  the  same  rela. 
tive  positions. 

For  what  is  slate  used  ?  For  what  are  clays  employed  ? 
Is  there  any  regular  order  of  arrangement  of  the  rocks  over 
each  other  ?  What  is  the  position  of  coal,  compared  with 
that  of  rocks  containing  salt?  Do  rocks  have  the  same 
relative  positions  in  all  countries  ? 


STRATIFICATION.  73 

This  is  a  fact  of  much  practical  utility ;  and  by 
it,  in  connection  with  some  others,  a  man  is  enabled 
to  say  whether  any  particular  rock  or  mineral  may 
probably  be  found  in  any  district  of  country,  by 
knowing  the  rocks  exposed  there  to  observation. 
We  frequently  see  but  one  kind  of  rock  in  a  dis- 
tance of  several  miles,  but  more  frequently  there  are 
two  or  more. 

Few  rocks  have  their  layers,  or  strata,  in  a  hori- 
zontal position,  but  they  generally  slope,  or  dip 
downwards,  and  sometimes  they  stand  vertically 
upon  their  edges.  This  inclination  or  dip  of  the 
rocks,  is  of  great  importance,  as  rocks  are  thus 
brought  to  our  view  that  would  otherwise  be  buried 
deep  in  the  earth.  When 
strata  of  different  rocks,  in- 
cline, they  emerge  in  succes- 
sion upon  the  surface  of  the 
earth,  thus,  so  that  in  travelling  in  the  direction  of 
the  dip  you  may,  in  a  few  hours,  pass  over  many 
different  kinds  of  rock.  The  line  of  dip  is  the  direc- 
tion towards  which  the  rock  slopes.  The  line  of 
bearing  is  the  direction  along  which  the  rock  emer- 
ges, or  more  strictly,  it  is  the  line  of  intersection 
of  the  plane  of  the  stratum  with  the  horizontal  plane. 

"In  travelling  over  an  extent  of  country,  the 
direction  of  the  strata  is  characterized  by  sameness 
and  uniformity.  There  is  little  variety  in  the  pro- 

What  is  the  utility  of  a  knowledge  of  this  ?  Are  rocks 
generally  in  a  horizontal  position?  In  what  position  are 
they  observed  ?  Of  what  importance  is  this  inclination  of 
rocks  ?  In  travelling  across  the  strata  what  is  observed  ? 
What  is  the  line  of  dip  ?  What  is  the  line  of  bearing  ? 
7 


74  STRATIFICATION. 

ductions  of  the  land,  or  the  condition  and  employ, 
ment  of  the  inhabitants.  On  the  contrary,  in  travel- 
ling along  the  line  of  dip,  our  eyes  are  continually 
regaled  with  a  change  of  scenery.  Every  hill  has 
a  character  of  its  own ;  a  steep  ascent  on  one  side 
is  met  by  a  gentle  declivity  on  the  other.  A  poor 
soil  is  succeeded  by  one  of  remarkable  fertility." 
[Greenough }s  Geology.] 

The  developement  of  the  order  of  superposition 
of  rocks,  is  one  of  the  most  important  connected 
with  geological  science,  both  m  an  economical  and 
scientific  point  of  view. 

Many  practical  difficulties  obstruct  its  perfect 
accomplishment,  such  as  the  difficulty  of  finding 
the  junction  of  rocks,  their  imperfect  stratification, 
bent  and  contorted  strata,  faults,  &c.  "but  these 
difficulties  disappear  when  several  formations  of 
great  extent  are  compared  together,  and  the  order 
of  superposition,  and  the  relative  ages  of  the  rocks 
are  as  determinate  as  any  mathematical  problem.1' 
[Humboldt  on  Rocks.] 

A  knowledge  of  the  principles  and  phenomena  of 
stratification  is  of  much  practical  importance,  not 
only  to  the  geologist,  but  the  community  generally 
and  may  lead  to  the  discovery  of  many  useful  rock* 
and  minerals.  It  is  not  generally  necessary  to  bora 
through  rocks  to  ascertain  what  lie  below  them. 


What  is  most  important  in  an  economical  and  scientific 
point  of  view  ?  When  do  these  difficulties  disappear  ?  Of 
what  use  is  a  knowledge  of  stratification  ?  Is  it  necessary 
to  bore,  to  ascertain  the  rocks  below  or  above  any  particulai 
one? 


STRATIFICATION.  75 

There  is  a  regular  order  in  which  the  rocks  lie 
over  each  other :  knowing  this  arrangement,  and 
the  direction  in  which  the  rocks  dip,  we  know  that 

B  they  must 
emerge  in 
succession. 

Instead    of 

digging  or  boring  through  the  strata  at  A,  they  may 
be  examined  by  travelling  towards  B,  in  a  direction 
opposite  to  the  direction  of  the  dip.  The  bottoms 
and  sides  of  water  courses,  and  the  cliffs  in  the  hills 
and  mountains,  are  the  situations  where  the  rocks 
can  be  examined  to  the  greatest  advantage. 

In  this  way,  as  the  different  strata  emerge  in  suc- 
cession, they  can  be  examined  with  any  required 
degree  of  attention,  and  better  than  by  boring,  as 
then  but  a  very  small  portion  of  the  rock  can  be  ex- 
posed  to  observation.  If  the  line  of  dip  be  known, 
the  line  of  bearing  is  also  known,  for  it  is  at  right 
angles  to  it.  If  the  line  of  bearing  be  known,  the 
direction  of  the  dip  does  not  follow,  for  it  may  dip 
in  two  directions  from  that  line,  thus, 
as  the  sides  of  a  roof  from  the  ridge. 
When  rocks  dip,  their  inclination  is 
expressed  in  degrees  of  the  quadrant.* 


How  would  you  ascertain  their  positions  ?  What  situations 
are  most  favourable  for  examination  ?  If  the  line  of  dip  be 
known,  is  the  position  of  the  line  of  bearing  known  ?  and  the 
reverse  ? 

*  The  quadrant  is  one  quarter  of  a  circle.  A  circle  is  divided  into 
360  degrees,  and  of  course,  the  quadrant  contains  90  degrees,  or  equal 
parts. 


76  STRATIFICATION. 

Whatever  the  angle  or  degree  of  inclination  may 
be,  the  thickness  of  the  stratum  is  measured  by  a 
line  perpendicular  to  the  plane  of  the  stra- 
tum, (as  seen  in  the  margin.)  When  the 
edges  of  the  strata  project  from,  or  show 
themselves  on  the  surface  of  the  earth,  they 
are  said  to  out  crop,  and  the  projection  is  termed  the 
crop  out  of  the  strata. 

Strata  generally  lie  upon  each  other  like  the 
leaves  of  a  book,  and  then  they  are  said  to  be  con- 
formable  strata.  Sometimes  other  sets  of  strata  lie 
upon  the  last,  which  are  conformable  among  them- 
selves, but  not 
to  the  first, 
thus,  and  they 
are  then  said 
to  be  unconformable. 

It  is  necessary  to  distinguish  strata,  from  the 
thin  slaty  layers  into  which  some  rocks  divide. 
When  rocks  are  divided  into  regular  layers  of  con- 
siderable extent,  they  are  said  to  be  stratified. 

The  planes  of  stratification,  and  those  in  which 
the  rocks  most  readily  split,  are  not  always  the 
same;  arid  this  is  remarkably  the  case  in  slate. 
The  strata  and  thin  layers  into 
which  this  rock  splits,  are  ar- 
ranged thus,  the  coarse  lines 
representing  the  strata  seams,  and  the  fine  ones  the 
thin  layers  of  slate. 

How  is  the  thickness  of  a  stratum  measured  ?  What  is 
the  outcrop  of  strata  ?  What  are  conformable,  and  uncon- 
formable strata  ?  What  is  the  distinction  between  layers  and 
strata  1 


STRATIFICATION. 


77 


There  is  frequently  some  difficulty  in  determin. 
ing  the  true  planes  of  stratification  in  slaty  rocks ; 
but  if  one  fact  be  kept  in  mind,  the  difficulty 
vanishes.  This  fact  is,  that  the  strata  vary  in  their 
texture ;  some  are  very  fine  grained,  some  are  coarse 
as  a  sandstone  and  the  planes  of  these  beds  of  diffe- 
rent materials,  or  of  various  textures,  indicate  the 
direction  of  the  planes  of  stratification. 

Clays  are  also  often  divided  by  parallel  seams, 
making  an  angle  with  the  strata  seams,  too  regular 
to  be  the  effect  of  chance,  they  must  be  regulated 
by  some  law  of  nature. 

Some  clays  break  into  regular  rhombic  figures, 
as  regular  in  their  forms  as  crystals. 

Strata  vary  from  a  few  inches  to  several  feet  in 
thickness. 

Strata  are  not  always  plane  surfaces, . 
but  are  often  curved,  or  bent,  thus. — 

Sometimes  the 
layers  are   much 
bent  in  various  directions,  (as 
seen  in  the  margin,)  and  the 
rocks  are  then  said  to  be  con- 
torted.* 


What  fact  if  observed  dispels  the  difficulties  found  in  de- 
termining the  true  planes  of  stratification  ?  What  inference 
must  be  drawn  from  clays  being  often  divided  by  parallel 
seams  ?  Into  what  figures  do  some  clays  break  ?  Do  the 
layers  of  slate  correspond  with  the  strata  ?  Are  strata  always 
in  plane  layers  ?  What  are  contorted  strata  ? 

*  M.  Ramond,  in  speaking  of  the  compact  and  argillaceous  lime- 
stones and  slates  of  Estaube,  and  the  sandy  limestone,  breccias,  and 
grits  of  Mont  Perdu,  says:  "They  seem  to  have  been  driven 
against  one  another  by  opposite  forces,  which,  at  the  point  of  contact, 

7* 


78  STRATIFICATION. 

Unless  care  be  taken  to  ascertain  the  direction 
of  the  dip,  the  apparent  dip  is  very  apt  to  be  mis- 
taken for  the  real  one.  If  the  edges  of  the  rock  be 
examined  in  the  direction  of  the  line  of  bearing,  the 
strata  appear  to  be  horizontal,  when  by  examina- 
tion in  other  directions,  they  would  be  found  con- 
siderably inclined. 

The  following  figure  will  perhaps  serve  to  illus- 
trate. The  end  of  the 
figure  represents  the 
inclination,  and  the  top 
and  long  side  show  the 
strata  edges  in  the  direction  of  the  line  of  bearing. 
A  person  should  never  judge  of  the  dip  of  strata, 
from  seeing  a  section  in  only  one  direction,  but  should 
always  seek  to  see  sections  in  at  least  two  directions, 
from  which  he  can  obtain  data  for  calculating  the 
true  dip. 

In  most  instances,  a  practiced  eye  would  be  able 
to  judge  of  the  direction  and  amount  of  the  dip  j 

Is  there  any  liability  to  mistake  the  direction  or  quantity 
of  dip  ?  What  precaution  should  be  taken  in  judging  of  the 
dip  of  strata  ?  Where  the  direction  and  amount  of  the  dip, 
and  the  direction  of  the  line  of  bearing  of  the  strata  is  of  par- 
ticular practical  utility,  what  should  be  done  ? 

have  shivered  them  into  short,  irregular,  tortuous  veins,  tne  entangle- 
ment of  which  forms  the  intervening  masses.  Figure  to  yourself," 
says  he,  "  a  number  of  viscid  liquors,  differently  coloured,  spreading 
themselves  in  whirling  laminae  in  the  vessel  in  which  they  are  poured, 
— watch  a  thick  column  of  smoke  floating  in  the  air, — you  will  have  be- 
fore you  an  image  of  the  confusion  which  prevails  in  these  rocks.  The 
struggle  of  two  conflicting  masses,— the  repeated  assaults  of  the  one, 
the  perservering  resistance  of  the  other,  this  is  the  idea  naturally  sug- 
gested on  contemplating  the  contorted  veins  in  these  rocks.  'Tis  a 
sea  consolidated  in  a  storm,  the  violence  of  which  may  still  be  seen  in 
the  petrified  waves."—  GreenougWs  Geology. 


STRATIFICATION.  79 

but  where  the  determination  of  these,  and  the  direc- 
tion of  the  line  of  bearing  of  the  strata  is  of  any 
particular  practical  utility,  as  in  opening  mines, 
quarries,  &c.,  the  direction  by  compass  of  a  small 
vertical  plane,  on  each  of  the  two  sections,  and  the 
angular  dip  of  the  lines  of  stratification  on  those 
vertical  sections,  should  *be  measured.  Data  are 
thus  afforded  for  trigonometrical  calculation  of  the 
direction  of  the  line  of  bearing,  and  of  the  dip  with 
its  exact  angle. 

There  is  another  error  that  may  be  committed  by 
a  person  not  attending  closely  to  the  dip  and  direc- 
tion of  the  strata.  "  Suppose  a  hill  to  be  covered 
with  vegetable  soil,  and  a  quarry  or  pit,  was  made 
in  it  near  the  bottom,  as  at  A,  the  stone  was  disco- 
vered to  be  sandstone ;  suppose  another  pit  had  been 
B  sunk  near 

the  sum- 
mit,  at  B, 
which  cut 

into  limestone.  It  might  be  supposed  that  the  lime- 
stone lay  over  the  sandstone  stratum,  when  it  is  in 
reality  below  it."  In  this  particular  instance  two 
strata  intervene  in  the  figure. 

In  limestone  mountains,  the  fissures  are  apt 
to  be  mistaken  for  strata  seams.  These  partings 
and  seams  are  sometimes  nearly  vertical,  when  the 
starta  are  horizontal.  These  sometimes  enlarge 


What  is  the  result  ?  Is  there  any  liability  to  mistake  the 
positions  of  rocks  on  hills  ?  What  causes  the  difficulty  of 
ascertaining  the  stratification  of  limestone  in  some  cases  ? 
Do  these  strata  ever  appear  vertical,  when  they  are  in  realitv 
horizontal  ? 


80 


STRATIFICATION. 


so  as  to  be  more  conspicuous  than  the  strata  seams. 
"  To  add  to  the  difficulty  it  very  frequently  hap- 
pens, that  a  calcareous  deposition,  like  a  coat  of 
plaster,  covers  the  face  of  a  rock ;  this  has  been 
formed  by  water  running  over  the  surface  and  de- 
positing calcareous  particles  upon  it. 

"  This  deposition  sometimes  conceals  the  strati- 
fication seams,  as  completely  as  a  coat  of  plaster 
covers  the  rows  of  brick  in  a  building.  The  ver- 
tical seams  or  partings,  are  sometimes  open,  and 
sometimes  have  formed  parallel  ridges  which  efface 
the  appearance  of  the  strata  seams  in  one  part  of 
the  rock,  but  not  in  the  other ;  and  in  such  instances, 
we  have  apparently  a  mountain  mass,  in  which  the 
strata  are  partly  horizontal  and  partly  vertical." 
[BdkeweWs  Geology.] 

In     the     accom- 
panying figure,  a,  a, 
are  the    apparently 
vertical   strata  and 
b,  b,  the  horizontal 
and  proper  strata. 
Strata  generally  appear  to  terminate  at  their  out 
crop.     When  the  strata  are  bent,  the  same  strata 
may  often  be  found  again  not  far  from  their  appa- 
rent termination,  as  may  be  observed  in  the  figure. 
The  strata  that  appear  to  terminate  near  A,  are 
35  C    found    again 

on  the  other 
side  of  A;  the 
curvature  or 


Do  strata  always  terminate  at  their  outcrop  ? 


STRATIFICATION.  81 

dip  varying,  they  approach  and  then  recede  from 
the  surface,  dipping  in  opposite  directions  at  A,  B 
andC. 

A  stratification  analogous  to  this,  is  often  ob- 
served adjacent  to  some  of  the  mountain  ranges, 
where  the  strata  appear  to  rest  against  the  sides  of 
the  mountain  masses  ;  d 
being  the  mountain,  and 
a  a,  b  b,  c  c,  similar  strata 
of  rocks. 

There  is  another  in- 
stance in  which  the  strata  may  not  terminate  at 
their  outcrop,  but  appear  again  in  the  opposite  hill, 
as  a  a,  but  b  6,  by  its  prolongation,  would  pass  over 
the  hill  C. 

C  Where  the  strata 

are  nearly  horizon- 
tal similar  strata  are 
almost  always  found 

on  the  opposite  sides 

a  of  a  valley,  as  if  they 

had  been  formerly  continuous,  and  the  valley  since 
formed  by  some  powerful  cause. 

There  is  another  point  in  relation  to  stratification, 
(and  it  is  also  applicable  to  veins,  in  rocks  that  are^ 
not  stratified,)  that,  from  its  practical  importance 
in  mining,  should  be  well  understood.  The  bed  of 
coal,  or  vein  of  ore,  appears  suddenly  to  terminate. 


Do  strata  rest  or  lean  against  mountains  ?  Does  the  same 
stratum  ever  appear  on  the  opposite  sides  of  valleys  ?  When 
beds  of  coal  terminate  suddenly,  can  they  be  regained  ?  and 
how? 


82 


STRATIFICATION. 


a  When  this  occurs, 
b  the  bed  may  be  found 
again,  either  above  or 
below  its  original  level. 
At  its  apparent  termi- 
nation, a  fissure,  or  else 
a  different  kind  of  rock,  occurs,  generally  in  the 
form  of  a  vein,  as  c  c. 

Repeated  observation  has  shown,  that  if,  at  the 
apparent  termination,  the  rock  cutting  it  off  inclines 
towards  you,  so  as  to  project  over  your  head,  the  bed 
of  coal,  or  other  mineral,  lies  at  a  lower  level  on  the 
other  side  of  c  c,  as  though  the  mass  of  strata  on 
one  side  of  the  vein  had  slid  down  to  a  lower  level. 
In  the  figure,  a  a  and  b  b  represent  beds  of  coal  cut 
off  by  the  vein  or  dyke,  c  c.  In  proceeding  from 
a  to  a,  the  reverse  of  the  above  would  take  place. 

Analogous  appearances  are  sometimes  presented 
upon  the  surface  of  the  earth,  where  there  are  high 
precipices  of  rock  in  successive  ranges  of  hills,  as 
a  &  a  in  the  figure. 

The  same  strata 
o  --  apparently  occur 
in  each  succes- 
sive ridge,  and  the  strata  all  dip  in  the  direction  a  b, 
and  the  masses,  forming  the  ranges  of  hills  appear 
to  have  cracked  off,  and  each  succeeding  mass  to 
have  slid  down  over  the  cliff  of  the  preceding. 


"What  has  been  observed  of  the  positions  of  the  beds  of  coal, 
in  reference  to  the  sloping  of  the  vein  or  dyke  ?  What  appears 
to  have  caused  the  present  position  of  the  beds  ?  Is  there 
any  analogous  appearance  in  the  hills  on  the  surface  of  the 
earth  ?  and  what  is  the  appearance  presented  by  such  hills  ? 


STRATIFICATION.  83 

"  In  the  coal  formation  at  Newcastle  in  England, 
the  strata,  at  distances  of  2  or  3  miles,  are  shattered 
by  fissures  which  extend  many  leagues.  Where 
these  fissures  occur,  the  strata  have  been  dislocated, 
and  the  subsidence  amounts  in  some  instances  to 
1000  feet ;  yet,  the  surface  of  the  earth  is  uniform 
and  level,  which  shows  the  immense  mass  of  mate- 
rials that  must  have  been  removed  and  deposited  to 
conceal  thus  these  subterranean  mountains."  [Rep. 
Brit.  Association,  i.  381. 

The  various  phenomena  of  stratification  indicate, 
that  powerful  forces  have  been  put  in  action,  thus 
to  bend  and  break  up  the  solid  strata  of  the  globe. 
In  some  parts  of  the  world,  the  stratified  masses  of 
great  extent  are  thrown  into  every  variety  of  posi- 
tion, and  as  much  confusion  prevails  in  their  ar- 
rangement, as  in  the  masses  of  ice  that  we  see  in 
our  rivers,  where  the  currents  or  tides  have  brought 
large  fields  of  it  crushing  against  others,  breaking 
them  into  large  fragments,  thrusting  and  overwhelm- 
ing them  in  every  direction,  and  the  frost  cementing 
them  thus  together. 

What  is  observed  of  the  coal  formation  at  Newcastle? 
What  does  it  show  ?     What  do  the  phenomena  of  stratifica. 
,  tion  indicate  ?     What  is  said  of  confused  stratification  ?     To 
what  is  it  compared  ? 


84  FORMATIONS. 

CHAPTER  V. 
FORMATIONS. 

When  a  series  of  strata  of  a  similar  rock,  are  ar- 
ranged with  occasional  strata  of  other  rocks  inter- 
vening, which  recur  in  different  parts  of  the  series, 
they  are  regarded  as  having  been  formed  during  the 
same  epoch,  and  under  similar  circumstances  ;  and 
such  series  are  called,  by  geologists,  Formations. 
Thus  the  strata  of  sandstone,  slate,  limestone,  &c. 
accompanying  coal,  are  altogether,  called  the  cool 
formation. 

Humboldt's  definition  of  a  formation  is,  "  an  as- 
semblage of  mineral  masses  so  intimately  connected, 
that  it  is  supposed  they  were  formed  at  the  same 
period,  and  that  they  present  in  the  most  distant 
parts  of  the  earth,  the  same  general  relations  both 
of  composition  and  relation  to  each  other."  [Hum- 
boldt  on  Rocks,  p.  1.] 

Some  formations  are  called  independent  forma- 
tions, and  that  which  is  considered  a  proof  of  the 
"  independence  of  a  formation  is  its  immediate  super- 
position on  rocks  of  a  different  nature  which  ought, 
consequently  to  be  considered  as  more  ancient." 
Trap  and  volcanic  rocks  are  an  exception  to  this 
rule.  [Humboldt  on  Rocks,  p.  6.] 


What  are  formations  ?  What  is  Humboldt's  definition  of 
a  formation  ?  What  is  the  proof  of  independant  formations  ? 
What  are  exceptions  to  this  rule  ? 


FORMATIONS.  85 

Some  formations  are  called  geological  equiva- 
lents because,  although  they  may  differ  in  their  ex- 
ternal  appearance,  and  in  mineralogical  and  chemi- 
cal composition,  they  contain  similiar  assemblages 
of  organic  remains  ;  and  have  the  same  geological 
position. 

Humboldt's  parallel  formations  are  equivalents 
that  replace  or  represent  each  other. 

Among  the  various  proofs  of  equivalent  forma- 
tions in  the  most  distant  parts  of  the  earth,  is  the 
identity  of  the  organic  bodies  buried  in  beds  having 
a  similar  geological  position.  \Humboldt  on  Rocks, 
p.  44.] 

When  formations  succeed  each  other,  it  is  usually 
the  case  that  strata  and  beds  of  the  one,  begin  at 
first  to  alternate  with  the  other  ;  until  after  these 
preludes  to  a  change,  a  new  formation  appears  with- 
out any  subordinate  beds.  [Humboldt  on  Rocks 
p.  14.  Relation  Historique,  ii.  p.  140.] 

The  idea  may  have  been  derived  from  what  pre- 
cedes, that  all  rocks  are  stratified,  but  it  is  not  so. 
Many  show  no  traces  of  stratification,  but  are  in 
large  shapeless,  mountain  masses,  as  granite,  sienite, 
porphyry,  &c. 

All  rocks,  whether  stratified  or  not,  are  traversed 
by  veins  of  various  mineral  substances.     Most  of* 
the  metallic  ores  are  found  in  veins.     Veins  appear 
to  have  been  once  open  fissures,  formed  by  the 

What  are  geological  equivalents  ?  and  what  proof  is  given 
of  them  ?  When  formations  succeed  each  other  what  is 
usually  the  case  ?  Are  all  rocks  stratified  ?  What  are  all 
rocks  traversed  by  ?  Where  are  most  of  the  ores  found  ? 
What  are  veins  ? 

8 


86  FORMATIONS. 

cracking  of  the  strata,  and  since  filled  with  the  sub- 
stances  now  occupying  them. 

The  walls  of  a  vein  are  the  rocks  contiguous  to 
it.  The  upper  side  of  the  vein,  when  inclined,  is 
called  the  roof,  and  the  lower  the  floor.  In  the 
same  rock,  there  are  frequently  several  systems  of 
veins,  formed  at  different  times,  and  then  we  can  tell 
the  relatives  ages  of  each,  for  the  oldest  is  inter- 
sected by  all,  and  the  newest  is  not  crossed  by  any 
of  the  others.  Veins  vary  from  a  few  lines  to  many 
feet  in  breadth.  They  are  sometimes  of  the  same 
materials  as  the  rock  traversed  by  them,  but  gene- 
rally different. 

It  has  been  observed,  that  all  the  rocks  might  be 
referred  to  two  general  classes,  which  were  called 
the  primitive  and  secondary  rocks.  Geologists  have 
since  arranged  rocks  into  a  greater  number  of 
groups. 

A  class  of  rocks  was  observed  that  had  some  of 
the  crystalline  structure,  like  primitive  rocks,  and 
the}7  also  contained  the  remains  of  animals  imbedded 
in  their  mass.  From  these  rocks  showing  charac- 
ters intermediate  between  the  primitive  and  secon- 
dary rocks,  they  were  called  transition  rocks.  There 
is  another  class  constituting  the  more  recent  rocks, 
called  tertiary  rocks. 


How  do  they  appear  to  have  been  formed  ?  What  are  the 
walls  of  a  vein  ?  What  its  roof?  What  its  floor  ?  Is  there 
often  more  than  one  system  of  veins  ?  How  can  the  relative 
ages  of  the  veins  be  determined  ?  Are  veins  ever  of  the 
same  material  as  the  rock  ?  Into  what  two  classes  can  rocks 
be  divided  ?  What  are  transition  rocks  ?  What  secondary  ? 
What  are  tertiary  rocks  ? 


FORMATIONS.  87 

More  recent  still,  in  point  of  time,  are  the  depos- 
ites  of  sand,  clay  and  gravel,  that  we  see  almost 
every  where,  and  which  cannot  have  been  placed  in 
their  present  position  hy  the  action  of  water,  run- 
ning  as  it  does  in  the  present  water-courses.  This 
is  called  dihrnion,  or  a  diluvial  deposit,  from  its  hav- 
ing been  deposited,  apparently,  during  the  deluge. 

Most  recent  of  all  is  the  alluvion,  or  alluvial  de- 
posit, which  is  now  forming  by  the  action  of  water 
and  winds.  The  mud  and  sand  brought  down  by 
rivers  and  torrents,  and  deposited  in  a  different  situa- 
tion from  what  it  had  before,  is  alluvion. 

These  classes  of  rocks  and  deposites,  arranged  in 
the  order  in  which  they  occur  naturally,  are  ; 

1  ALLUVIAL  deposites ;     4  SECONDARY  rocks ; 

2  DILUVIAL         «  5  TRANSITION     " 

3  TERTIARY  rocks  ;         6  PRIMITIVE       " 

Within  a  few  years,  it  has  been  proposed  to  sub- 
stitute other  names,  upon  the  ground  that  these  in- 
;roduce  theoretical  considerations,  as  to  the  time,  or 
mode,  of  formation  of  the  rocks.  If  such  names  be 
substituted  as  may  suggest  the  idea  of  relative  posi- 
tions only,  observers  will  be  less  apt  to  be  influenced 
by  particular  theories,  when  they  come  to  the  ob- 
servation of  facts. 


What  are  alluvial  deposits  ?  What  diluvial  ?  What  is  the 
jrder  in  which  these  classes  of  rocks  and  deposits  are  arranged  ? 
For  what  reason  has  it  been  proposed  to  substitute  other 
iam.es  for  those  just  mentioned  ? 


88  FORMATIONS. 

In  conformity  with  this  plan,  Conybeare  and 
Phillips  have  arranged  rocks  in  five  classes,  viz  : 

1  SUPERIOR;  3  MEDIAL ;         5  INFERIOR. 

2  SUPERMEDIAL  ;     4  SuBMEDIAL  ; 

In  this  classification,  the  coal  formation,  in  the 
lower  part  of  the  secondary  of  the  other  arrange- 
ment, is  taken  as  the  medial  class ;  the  submedial 
corresponding  with  the  transition,  and  the  inferior 
to  the  primitive  rocks.  The  supermedial  embraces 
the  upper  part  of  the  secondary  class,  and  the  supe- 
rior, the  tertiary  rocks  and  the  diluvial  and  alluvial 
deposites. 

De  La  Beche  has  also  given  a  classification  of 
rocks  that  is  very  good.  He  makes  two  general 
classes,  like  Lehman,  calling  them  Superior  and  In. 
ferior  rocks ;  the  first  comprehending  all  the  rocks 
containing  fossils,  and  the  latter  corresponds  with 
the  primitive  rocks. 

The  first,  or  superior  rocks,  are  divided  into 
groups,  according  to  the  arrangement  of  the  organic 
remains  contained  in  them.  The  inferior,  are  di- 
vided into  stratified  and  unstratified  rocks,  and  they  : 
are  described  in  the  usual  manner. 

The  arrangement  which  has  been  generally  em- ; 
ployed  in  describing  the  rocks,  will  be  adhered  to 
in  this  treatise,  as  more  convenient,  and  more  easily 


What  is  Conybeare  and  Phillips'  arrangement?  Wha 
formation  is  assumed  as  the  medial  ?  To  what  do  the  infe 
nor,  submedial,  supermedial  and  superior  correspond  in  th 
former  classification  ?  What  is  De  La  Beche's  arrangement " 


FORMATIONS.  89 

applied  by  those  who  have  made  no  great  progress 
in  a  knowledge  of  fossils. 

The  rocks  will  be  described  in  the  order  of  their 
position,  beginning  with  the  lowest. 

"  If  any  rocks  can  with  propriety  be  denominated 
primary,  or  primitive,  they  are  those  which  are 
most  widely  spread  over  the  globe,  in  the  lowest  re- 
lative  situation,  and  which  contain  no  remains  of 
organic  existence.  Primary  rocks  are  .supposed, 
by  geologists,  to  constitute  the  foundation  on  which 
rocks  of  all  the  other  classes  are  laid ;  and  if  we  take 
an  enlarged  view  of  the  structure  of  the  globe,  we 
may  admit  this  to  be  the  fact, — but  the  admission 
requires  certain  limitations." 

The  same  causes  that  have  produced  certain  rocks 
in  masses  of  great  extent  below  all  the  other  rocks, 
have,  in  certain  situations,  reproduced  them  in 
smaller  masses,  covering  the  transition  and  secon- 
dary rocks. 

"  The  structure  of  primary  rocks  is  crystalline ; 
they  form  the  central  parts  of  the  most  elevated 
mountain  chains,  and  they  occur  at  the  lowest  depths 
that  have  been  yet  explored,  and  are  hence  believed 
to  be  the  most  ancient  of  the  rock  formations." 

The  principal  rocks  called  primitive,  are — 

1  GRANITE  ;  3  MICA  SLATE. 

2  GNEISS,  or  SLATY  GRANITE  ; 

There  are  some  other  primary  rocks  that  occur 

What  are  primitive  rocks,  and  what  are  they  supposed  to 
constitute  the  foundation  of?    What  is  the  structure  of  prim- 
itive rocks  ?    What  are  the  principal  primative  rocks  ?^ 
/  8* 


90  GRANITE. 

imbedei  in,  and  interstratified  with,  the  principal 
primitive  rocks.  They  are  called  subordinate  rocks. 
They  are— 

HORNFL^NDE  ROCK  ;  CRYSTALLINE  LIMESTONE  ; 

SERPENTINE       "  QUARTZ  ROCK. 

"  The  three  principal  rocks  of  the  primary  class, 
granite,  gneiss  and  mica  slate,  might  with  propriety 
be  regarded  as  belonging  to  one  formation.  They 
are  con-posed  essentially  of  the  same  minerals,  vary- 
ing in  rifferent  proportions,  and  are  rather  modes  of 
the  same  rock,  than  different  species.  They  pass 
by  gradation  into  each  other,  as  one  or  other  of  their 
constituent  minerals  becomes  more  or  less  abun- 
dant ;  they  alternate  with  each  other  in  various 
situations,  and  may  be  regarded  as  cotemporaneous. 
It  may,  however,  for  convenience  of  description,  be 
proper  to  treat  of  each  separately." 

GRANITE. 

Granite  is  an  aggregation  of  grains,  or  masses  of 
quartz,  feldspar,  and  mica,  adhering  to  each  other 
without  any  cement.  The  feldspar  and  mica  are 
generally  crystalline,  but  the  quartz  rarely  shows 
this  structure. 


What  are  the  subordinate  primitive  rocks  ?  Do  granite, 
gneiss  and  mica  slate  belong  to  one  formation  ?  Do  they 
bear  any  analogy  with  each  other  ?  Do  they  alternate  with 
each  other  ?  Of  what  minerals  is  granite  composed  ?  Are 
the  minerals  crystalline  1 


GRANITE.  91 

The  minerals  of  which  granite  is  composed  are 
aggregated  differently  in  different  granitic  rocks, 
and  often,  even  in  the  same  rock,  the  grains  and 
crystals  in  one  part  of  the  rock  are  coarse,  in  the 
other  fine ;  and  perhaps  one  of  the  minerals  may 
predominate  in  one  part,  and  be  in  small  quantities 
in  another. 

When  granite  or  any  other  rock  is  fine  grained, 
with  lar^e  crystals  of  feldspar  imbedded,  it  is  said  to 
be  porphyritic. 

Feldspar,  in  general,  constitutes  by  far  the  largest 
part  of  granite,  and  its  colours  are  various,  but  gen- 
erally white  or  red.  The  mica  is  variable  also,  in 
colour,  but  is  generally  black  or  white. 

Sometimes  other  minerals  replace  the  mica  en- 
tirely, or  in  part,  in  granite,  without  altering  its  gen- 
eral character.  When  hornblende  -supplies  the 
place  of  mica,  the  rock  is  called  sienite,  and  when 
talc,  or  chlorite  enters  into  the  composition,  it  is 
called  talcose,  or  chloritic  granite,  and  sometimes 
protogine. 

"  Granite  is  considered  as  the  foundation  rock  on 
which  slate  and  all  secondary  rocks  are  laid."  When 

granite  rises  above 
the  surface,  the  beds 

°^   °tner    rocks>    V1 

_  the   same    district, 
rise  toward,  and  lie  against  it,  thus ;  but  there  are 

Are  the  minerals  aggregated  in  different  proportions  in 
granite  ro^ks  ?  When  are  rocks  porphyritic  ?  Which  min- 
eral predominates  in  granite  ?  What  is  sienite  ?  and  what 
is  protogine  ?  How  do  rocks  lie  in  the  vicinity  of  granite 
mountains  ?  Do  they  ever  pitch  or  dip  under  granite  ? 


92  GRANITE. 

instances  where  they  appear  to  pitch  under  the  gra. 
nite,  as  seen  in  the  figure. 

The    aspect    of    granite 
mountains  is  extremely  vari- 
ous.    When   the    beds   are 
horizontal,  or  when  the  rock  is  soft  and  disintegrat- 
ing, the  summits  are  rounded  and  unpicteresque.. 
When  hard  and  soft  granite  occur  in  the  same  mass, 
the  soft  decomposes,  and  leaves  the  hard  in  large, 
loose  masses  upon  the  soil,  or  if  they  lie  in  alternate 
>^1  f~\  f*\  A        a      Eighty  inclined  beds,  the 
[     y     Lj      I/  V^v  hard  granite  forms  high  and 

— v     * — •***  almost  inaccessible  peaks,  as 

seen  in  the  figure. 

Masses  of  granite  are  commonly  divided  by  fis- 
sures into  large  blocks,  which  often  ap- 
proach to  a  rhomboidal  form,  thus,  and 
sometimes  a  columnar  structure  may  be 
observed.  Granite  is  rarely  found  at  any 
great  elevation  in  the  United  States.  It  is  not  often 
observed,  except  in  beds  or  veins,  or  interstratified 
with  other  rocks  in  New  England. 

Granite  often  forms  veins,  traversing  the  super- 
incumbent  rocks.  This  is  a  fact  of  some  impor- 
tance in  a  geological  point  of  view. 

There  is  a  variety  of  granite  very  finely  granular, 
or  almost  compact,  called  by  the  English  geologists 


Does  the  aspect  of  granite  mountains  vary  ?  When  hard 
and  soft  granite  alternate  in  beds,  what  is  the  appearance  of 
the  mountains  ?  Into  what  shaped  masses  is  granite  often 
divided  ?  Does  granite  often  form  veins  ? 


GRANITE.  93 

compact  feldspar;   and  by  the  French,  described 
under  the  name  of  Eurite. 

Another  variety  of  granite  is  called  graphic  gran- 
ite. In  this  variety,  the  feldspar  greatly  predomi- 
nates, and  the  quartz  is  arranged  in  it  somewhat  in 
the  form  of  Chinese  letters,thus — 
This  variety  of  granite  decom- 
poses readily,  and,  during  its  de- 
composition, the  potassa,  or  soda, 
contained  in  the  feldspar  is  removed  by  the  rain,  or 
by  water  percolating  through  it,  and  leaves  a  clay 
used  in  the  manufacture  of  porcelain,  and  called 
kaolin  and  porcelain  clay. 

Oxide  of  tin  sometimes  replaces  the  mica  in  gran- 
ite and  then  it  takes  the  name  of  stanniferous  gran- 
ite. Stanniferous  granite  is  usually  much  disinte- 
grated, the  feldspar  passing  into  kaolin. 

Granite  supplies  a  durable  material  for  architec- 
ture, but  as  some  of  the  varieties  crumble  by  the 
action  of  the  weather,  care  is  required  in  its  selec- 
tion. In  selecting  proper  building  materials,  ob- 
serve whether  the  rock,  in  its  natural  situation,  and 
where  exposed  to  the  weather,  shows  any  appearance 
of  having  crumbled.  If  the  rock  is  firm,  and  not 
easily  crumbled,  where  it  has  been  long  exposed  na- 
turally, it  will  stand  well  if  put  into  buildings.  " 


What  is  eurite  ?  What  is  graphic  granite  ?  What  clay  is 
formed  by  the  decomposition  of  this  granite  ?  When  oxide 
of  tin  replaces  the  mica  in  granite  what  name  does  it  take  ? 
For  what  is  granite  used  ?  What  is  necessary  in  selecting 
granite  for  building  1 


94  GNEISS,  AND  MICA  SLATE. 

GNEISS,  AND  MICA  SLATE. 

Gneiss  and  mica  slate  are  often  interstratified 
with  each  other  and  with  granite,  and  are  generally 
considered  as  cotemporaneous,  or  formed  at  the 
same  time. 

Gneiss  is  composed  of  the  same  minerals  as  gran- 
ite ;  viz :  quartz,  feldspar,  and  mica,  and  is  a  slaty 
granite.  Granite  and  gneiss  pass  into  each  other 
by  almost  insensible  gradation.  If  in  granite  the 
feldspar  be  diminished  in  quantity,  and  the  mica  in- 
creased and  arranged  in  layers,  the  granite  loses  its 
massive  structure,  and  becomes  slaty,  and  then  we 
have  a  true  gneiss. 

Bakewell,  an  English  geologist,  who  has  been  a 
close  observer  of  facts,  thinks  that  the  stratification 
of  gneiss  has  been  confounded  with  its  slaty  struc- 
ture, and  this  structure,  he  thinks,  is  the  effect  of 
crystallization.  Gneiss  is  employed  for  ma  ny  pur- 
poses, among  which  are  :  for  building  and  flagging, 
and  some  varieties  are  good  stones  for  standing  fire 
in  furnaces,  fireplaces,  &c. 

Mica  slate,  or  micaceous  schistus,  as  it  is  some- 
times called,  is  composed  essentially  of  qu-u-tz  and 
mica.  Feldspar  is  not  uncommon  in  this  rock,  but 
is  not  esteemed  an  essential  constituent.  Mica 
slate  passes  by  slight  gradations  into  granite  and 
gneiss. 


Are  gneiss,  granite  and  mica  slate  interstratified?  Ot 
what  is  gneiss  composed?  How  does  granite  pass  into 
gneiss  ?  For  what  is  gneiss  employed  ?  Of  what  is  mica 
slate  composed  ? 


HORNBLENDE  ROCK.  95 

This  rock  is  very  fissile,  or  easily  split  in  one  di- 
rection ;  its  colour  is  generally  gray,  or  inclining 
to  green  or  yellow,  and  it  has  generally  a  pearly  or 
shining  lustre.  Mica  slate  and  gneiss  are  often 
bent  and  contorted.  Crystals  of  garnet  and  of 
staurolide  are  the  most  common  minerals  imbedded 
in  mica  slate. 

Mica  is  sometimes  either  entirely  or  in  part  re- 
placed by  talc  or  chlorite,  and  then  the  rock  is 
called  taJcose  and  cliloritic  slate.  Gneiss  and  mica 
slate  are  nearly  similar  in  their  constituents,  and 
geological  positions  ;  and  most  of  the  metalic  ores 
and  minerals  that  occur  in  one,  occur  also  in  the 
other.  Crystalline  limestone,  hornblende  and  ser- 
pentine, more  frequently  occur  in  mica  slate,  than 
in  gneiss. 

HORNBLENDE  ROCK. 

Rocks  in  which  hornblende  predominates,  are  not 
uncommon  in  beds  in  primitive  rocks.  When  the 
rock  is  slaty,  it  is  called  hornblende  slate  and  gneis- 
soid  hornblende.  Augite  rocks  are  also  not  uncom- 
mon. Hornblende  and  feldspar,  and  augite  and 
feldspar,  under  certain  circumstances,  form  partic- 
ular rocks,  which  will  be  discussed  under  the  terfn 
of  trap  rock. 


Is  it  fissile  ?  What  is  its  appearance  ?  Is  it  ever  con- 
torted?  What  are  the  minerals  imbedded  in  it?  When 
talc  or  chlorite  replaces  the  mica,  what  is  the  rock  called  ? 
What  subordinate  rocks  occur  most  frequently  in  mica  slate  ? 
When  hornblende  rock  is  slaty,  what  is  is  called  ?  Are  augite 
rocks  found  in  primitive  rocks  ? 


96  CRYSTALLINE  LIMESTONE. 

SERPENTINE  ROCKS. 

Serpentine  rocks  are  mostly  composed  of  serpen- 
tine, with  small  quantities  of  minerals  imbedded. 
Most  of  these  minerals  contain  magnesia  as  a  con- 
stituent. 

Serpentine  rock  sometimes  forms  mountain 
masses,  and  is  sometimes  magnetic.  Serpentine  is 
frequently  mixed  with  primitive  limestone,  and  then 
forms  a  beautifully  variegated  marble  of  various 
shades  of  green,  yellow,  black  and  white,  like  that 
near  New  Haven,  and  called  verd  antique  marble. 

CRYSTALLINE  LIMESTONE. 

Crystalline  limestone,  of  which  statuary  marble 
is  a  variety,  occurs  forming  immense  beds  in  gneiss 
and  mica  slate.  The  common  grave-stones  of  white 
marble,  are  of  this  limestone.  A  bed  of  this  rock 
extends,  with  few  interruptions,  700  miles  in  length ; 
beginning  in  Canada,  passing  through  Vermont,  the 
western  parts  of  Massachusetts  and  Connecticut 
thence  through  New  York,  New  Jersey,  &c.  to  Vir- 
ginia, and  is  extensively  quarried  in  a  great  many 
places,  and  supplies  most  of  the  marbles  used  in  this 
country.  Limestones  that  take  a  good  polish,  are 
called  marbles. 


Of  what  are  serpentine  rocks  composed  ?  What  substance 
do  most  of  the  minerals  that  occur  with  serpentine  contain  1 
Does  serpentine  ever  form  large  masses  ?  When  mixed  with 
limestone,  what  does  it  form  ?  In  what  rocks  is  crystalline 
limestone  found  ?  Does  it  form  extensive  masses  ?  Is  any 
instance  given  in  this  country  ? 


TRANSITION  ROCKS.  97 

QUARTZ  ROCK. 

This  rock  is  composed  of  grains  of  quartz,  aggre- 
gated without  cement.  It  is  usually  white  or  stained, 
or  shaded  with  gray,  red  and  yellow.  Its  structure 
is  slaty,  but  in  its  small  masses,  it  is  nearly  com- 
pact.  It  is  used  as  a  flagging  stone,  and  fire  stone. 


CHAPTER  VI. 
TRANSITION  ROCKS. 

Transition  rocks  lie  immediately  over  the  pri- 
mary ones  when  both  occur  together,  and  are  dis- 
tinguished from  the  lower,  or  primitive  rocks,  by 
their  containing  some  of  the  remains  of  plants  and 
animals.  The  transition  rocks  therefore  "  may  be 
regarded  as  the  most  ancient  records  of  our  globe, 
imprinted  with  the  natural  history  of  its  earliest  in- 
habitants." "Transition  rocks  are  the  principal 
repositories  of  metallic  ores,  which  occur  both  in 
beds  and  veins  more  abundantly  in  many  of  the  rocjje 
of  this  class,  than  in  primary  rocks." 


Of  what  is  quartz  rock  composed  ?  What  is  its  appear- 
ance  ?  What  its  structure  ?  and  what  its  uses  ?  How  are 
the  transition  rocks  situated  with  relation  to  the  primitive  ? 
How  distinguished  from  them  ?  In  what  class  of  rocks  are 
metallic  ores  abundant  ? 

9 


98  TRANSITION  ROCKS. 

Geologists  have  often  been  perplexed  in  their  at- 
tempts to  draw  a  well-marked  line  of  distinction  be- 
tween primary  and  transition  rocks  ;  the  difficulty 
has  arisen  chiefly  from  their  arranging  slate  with 
the  primary  class. 

"  So  long  as  it  may  be  proper  to  class  rocks  con. 
taining  organic  remains,  with  the  transition  rocks, 
we  must  place  slate  among  them.  Nor  can  this  be 
invalidated  by  the  fact,  that  in  some  slate  rocks,  no 
vestiges  of  animal  or  vegetable  remains  occur  ;  for, 
among  the  secondary  strata  abounding  in  such  re- 
mains, we  often  meet  with  alternating  beds,  in  which 
they  are  never  found ;  but  we  do  not,  on  that  ac- 
count, class  them  with  primary  rocks."  The  fol- 
lowing are  the  principal  transition  rocks,  slate  lying 
next  the  primitive  rocks  : 

1.  TRANSITION,  or  mountain  limestone  ; 

2.  GRAYWACKE,  and   graywacke  slate,  passing 
into  old  red  sandstone  ; 

3.  SLATE,  and  its  varieties. 

SLATE.  Roof-slate,  and  the  slate  of  which  school - 
slates  are  made,  are  well  known  varieties  of  this 
rock.  It  is  sometimes  called  clay  slate,  argillaceous 
slate,  and  argillaceous  scJiistus-.  There  is  a  soft  kind 
of  slate  occurring  with  coal,  and  called  slate  clay 
and  shale ;  this  must  not  be  confounded  with  clay 
slate.  The  colours  of  slate  are,  gray  of  various 
shades,  blue,  green,  purple  and  red. 

"  Slate  rocks  are  commonly  divided  into  beds  of 


What  rock  is  lowest  in  the  transition  rocks?  What  are 
the  principal  transition  rocks  ?  What  are  the  other  names 
for  slate  ?  What  mu&t  slate  not  be  confounded  with  ? 


TRANSITION  ROCKS.  99 

various  degrees  of  thickness,  which,  generally,  are 
much  elevated,  and,  from  the  natural  divisions  of 
the  rocks,  they  often  form  peaked  and  serrated 
mountains."  "  Slate  has  been  described  by  former 
geologists,  as  distinctly  stratified,  because  it  splits 
easily  into  thin  laminae,  and  the  direction  of  the 
laminae  is  asserted  to  be  in  the  direction  of  the  beds : 
but  in  opposition  to  the  authority  of  many  eminent 
geologists,  I  maintain  that  slate,  unless  it  be  of  a 
soft  or  coarse  kind,  approaching  to  shale  or  to  gray, 
wacke,  invariably  splits  in  a  transverse  direction 
to  that  of  the  beds,  making  with  that  direction  an 
angle  of  about  60  degrees."  Succeeding  observa- 
tions have  confirmed  the  above  statement. 

Slate  rocks  vary  much  in  quality  in  the  same 
mountains.  When  magnesia  enters  into  the  com- 
position of  slates,  they  are  distinguished  by  their 
green  colour,  and  pass  into  chloritic  and  talcose 
slates.  Whetstone  slate,  and  hone,  are  varieties  of 
talcose  slate,  containing  imperceptible  particles  of 
quartz. 

Roof  slate  is  generally  imbedded  in  a  coarse  slate. 
The  varieties  of  this  slate  are  preferred  that  split 
into  thin  even  layers,  with  a  smooth,  plane  surface. 
Slate  is  regarded  as  one  of  the  rocks  in  which  ore^ 
abound  more  than  in  any  other. 

Graywacke  and  graywacke  slate,  in  their  most 
common  forms,  may  be  described  "  as  a  coarse  slate, 

Is  slate  distinctly  stratified  ?  When  magnesia  enters  into 
the  composition  of  slate,  how  is  it  distinguished  ?  What 
are  whetstone,  slate  and  hone  ?  What  varieties  of  slate  are 
preferred  for  roofing  ?  Is  slate  a  metalliferous  rock  ?  De- 
scribe graywacke  ? 


100  TRANSITION  ROCKS. 

containing  particles  or  fragments  of  other  rocks  or 
minerals,  varying  in  size  from  two  or  more  inches, 
to  the  smallest  grain  that  can  be  perceived  by  the 
eye.  "  When  the  imbedded  particles  become  ex- 
tremely minute,  gray wacke  passes  into  slate.  When 
the  fragments  and  particles  are  numerous,  and  the 
slate  in  which  they  are  cemented  can  scarcely  be 
perceived,  graywacke  becomes  coarse  sandstone  or 
gritstone."  When  the  fragments  are  larger,  and 
angular  in  their  forms,  the  rock  forms  what  is  called 
a  breccia.  When  the  rock  contains  rounded  frag- 
ments and  pebbles,  it  is  called  pudding  stone. 

The  fragments  of  graywacke,  including  the  brec- 
cias and  pudding  stone,  are  always  of  the  lower 
rocks,  and  never  of  the  upper  strata. 

The  red  sandstone,  called  old  red  sandstone,  is  a 
graywacke,  coloured  red  by  the  oxide  of  iron.  There 
is  another  red  sandstone,  called  new  red  sandstone, 
occupying  a  much  higher  situation  in  the  geological 
series,  and  it  is  sometimes  difficult  to  distinguish 
them.  The  red  sandstone,  quarried  so  largely  for 
building,  near  Middletown,  Conn,  and  in  New  Jer- 
sey, is  by  some  thought  to  belong  to  one  of  these 
sandstones,  and  by  some  to  the  other. 

Red  sandstone  is  a  rock  of  considerable  impor- 
tance as  a  building  material.  Wlien  beds  of  clay, 
or  argillaceous  beds,  alternate  with  this  rock,  the 
soil  is  generally  very  fertile ;  but  where  the  sand* 


When  does  it  become  gritstone  ?  When  breccia  ?  When 
pudding  stone  ?  What  is  old  red  sandstone  ?  Is  it  ever  dif- 
ficult to  distinguish  between  the  old  and  new  red  sandstone  ? 
For  what  is  red  sandstone  employed  ?  What  are  the  agri- 
cultural characters  of  red  sandstone  ? 


TRANSITION  ROCKS.  101 

stone  alone  prevails,  the  land  is  mostly  a  sterile 
waste.  A  deposit  of  red  sandstone  extends  with 
few  interruptions,  from  Vermont,  through  Massa- 
chusetts and  Connecticut,  down  Connecticut  river 
to  Middletown,  thence  to  New  Haven,  thence  to  the 
Rappahannock,  in  Virginia,  a  distance  of  seven 
hundred  miles. 

Charred  wood,  fossil  bones  and  impressions  of 
plants  and  fish,  have  been  found  in  it,  and  in  the 
argillaceous  rocks  imbedded  in  it.  Copper  and  lead 
ores  are  found  in  it  in  some  places,  as  at  Simsbury, 
Ct. ;  Belleville,  Somerville,  &c.  New  Jersey ;  and 
Perkiomen,  Pennsylvania ;  and  these  ores  some- 
times contain  silver  and  gold  in  small  quantities. 

Transition,  or  mountain  limestone,  is  one  of  the 
most  important  of  the  transition  rocks.  Its  mineral 
characters  vary  considerably.  Its  usual  colour  is 
gray,  but  is  often  reddish,  brown,  or  black.  It  is 
often  much  variegated,  veined,  and  spotted. 

This  limestone  is  rarely  as  crystalline  as  primi- 
tive ;  or  so  compact  and  earthy  in  its  texture  as 
secondary  limestone.  It  often  alternates  with  slate 
and  graywacke  slate,  and  the  strata  are  sometimes 
remarkably  contorted.  It  is  the  mountain  lime- 
stone, upon  which,  as  a  basis,  the  coal  formation  is 
generally  found  resting.  . 

This  rock  contains  a  great  variety  of  organic 

Where  is  there  an  extensive  deposite  of  this  rock  ?  What 
fossils  have  been  found  in  it  ?  What  ores,  and  where  ?  Is 
transition  limestone  a  rock  of  any  importance  ?  Describe  it  ? 
What  does  it  alternate  with  ?  Are  the  strata  ever  contorted  ? 
Upon  what  does  the  coal  formation  generally  rest  ?  Does 
transition  limestone  contain  many  organic  remains  ? 
9* 


102  TRANSITION  ROCKS. 

remains,  and  the  individual  fossils  are,  in  some 
places,  exceedingly  numerous  ;  the  rock  in  fact  ap. 
pearing  to  be  formed  of  the  aggregated  remains  of 
coralline  animals,  and  of  those  having  a  shelly  cov- 
ering, called  testaceous  animals. 

Mountain  limestone  is  also  called  metalliferous 
limestone,  from  its  containing  large  quantities  of 
metallic  ores.  The  ores  found  in  this  rock  are 
mostly  lead  ores,  which  often  contain  a  considerable 
portion  of  silver.  The  lead  and  silver  obtained  in 
Derbyshire  England,  and  in  the  Hartz  mountains 
in  Germany,  are  from  this  rock ;  and  the  mines  of 
lead  in  Missouri  and  Illinois  are  in  this,  and  the 
associated  rocks,  and  in  the  soil  produced  by  their 
decomposition. 

This  limestone  is  also  called  encrinal  limestone, 
from  the  great  numbers  of  fossil  encrinites  imbedded 
in  it.    The  encrinites  are  sometimes  called 
screw-stones,  from  their  bearing  some  re- 
semblance in  form  to  a  screw,  thus. 

They  are  also  called,  in  common  Ian- ' 
guage,  wheel-whirls,  because  the  parts  seen  in  the 
sketch  separate  into  thin  circular  plates 
like  a  wheel,  and  generally  appears  thus. — 

The  heads  of  the  encrinite  are  often  found 
in  the  limestone,  and  are  mentioned  by 
people  unacquainted  with  fossils,  as  petrified  wal- 
nuts, petrified  acorns,  &c. 


And  of  what  classes  of  animals  ?  What  are  other  names 
for  mountain  limestone  ?  What  ores  are  most  abundant  in 
this  rock  ?  From  what  does  this  rock  derive  the  name  en- 
crinal limestone  ?  What  are  the  encrinites  sometimes  called  ? 
What  have  the  heads  of  the  encrinite  been  called  ? 


TRANSITION  ROCKS.  103 

It  is  almost  invariably  the  case,  that  mountain 
limestone  is  found  abounding  in  fissures  and  caverns. 
Most  of  the  caverns  in  England,  Germany  and  the 
United  States,  are  in  this  rock.  Rivers  that  flow 
in  it  are  often  suddenly  engulphed,  and  pursue,  for 
a  considerable  distance,  a  subterranean  course. 
Large  springs  and  streams  burst  suddenly  out  from 
the  hills. 

Where  this  rock  approaches  the  surface  of  the 
earth,  in  many  parts  of  England  and  of  the  United 
States,  it  shows  a  great  number  of  deep,  funnel- 
shaped  cavities,  some  of  them  100  or  more  yards 
across,  and  100  or  200  feet  deep,  and  some  only  a 
few  yards  in  width  and  depth.  In  England  they 
are  called  swallow  holes,  because  they  swallow  up 
the  streams  of  water  that  sometimes  run  into  them. 
In  the  United  States  they  go  by  the  name  of  sink 
holes,  because  the  earth  is  sometimes  observed  to 
sink  and  form  them. 

There  is  generally  a  cavity  in  the  bottom,  through 
which  the  water  is  conveyed  into  the  caverns  and 
Assures  underneath.  They  appear  to  have  been 
formed  by  the  water  running  in  the  fissures  of  the 
rock,  and  gradually  dissolving  it.  This  appears  to 
have  continued  until  the  spaces  became  so  large, 
that  the  rock  was  not  strong  enough  to  support  the 
superincumbent  weight,  and  by  falling  in,  caused 
the  earth  above  to  sink,  and  form  large  cavities 
upon  the  surface.  The  edges  of  these  cavities  con- 


What  does  this  limestone  abound  in  ?  What  is  said  of 
livers  and  springs  ?  Where  the  rock  approaches  the  sur- 
face,  what  are  observed  ?  Describe  the  sink  or  swallow 
holes  ?  How  do  they  appear  to  have  been  formed  ? 


104  SECONDARY  ROCKS. 

tinually  crumble  away,  until  the  cavity  has  a  fun- 
nel  shape,  sloping  steeply  down  on  all  sides  to  the 
centre. 

These  sink  holes  may  be  observed  in  great  num- 
bers a  few  miles  south  of  St.  Louis  Missouri ;  also 
in  some  parts  of  Kentucky,  Tennessee,  Illinois,  &c. 
The  great  caverns  in  some  of  those  states,  com- 
municate with  numbers  of  these  cavities,  and  in 
some  places,  the  light  may  be  seen  through  the  hot- 
torn  of  the  sink  holes,  by  the  observer,  when  stand- 
ing in  the  caverns  below. 

Nodules  of  hornstone  sometimes  resembling  flint, 
are  seen  in  this  limestone  in  many  parts  of  the 
country. 

Mountain  or  transition  limestone  is  generally 
sufficiently  firm  to  take  a  good  polish,  and  from  its 
being  often  beautifully  variegated,  it  is  used  as  a 
marble.  It  also  makes  good  lime  when  burnt. 


CHAPTER  VII. 
SECONDARY  ROCKS* 

Geologists  now  divide  the  secondaiy  rocks,  into 
upper  secondary,  and  lower  secondary.  The  most 

Where  may  these  holes  be  observed  ?  Do  they  ever  com- 
municate with  caverns  ?  What  mineral  occurs  imbedded  in 
the  form  of  nodules  ?  Does  transition  limestone  take  a  good 
polish  ?  For  what  is  it  employed  ?  What  two  great  divis- 
ions are  made  of  the  secondary  rocks  ? 


SECONDARY  ROCKS.  105 

,mportant  rock  formations,  in  an  economical  point 
of  view,  are — 

The  coal  formation  in  the  lower  secondary  series, 
and  the  rock  salt  or  saliferous  formation  in  the  upper 
secondary. 

The  rocks  associated  with  coal,  are  called  coal 
measures.  The  coal  measures  consist  of  a  series  of 
alternating  layers  of  coal,  slate,  sandstone,  arid  some- 
times limestone,  the  alternations  being  frequently 
and  indefinitely  repeated. 

The  sandstones  of  the  coal  formation  are  quite 
tender  and  micaceous.  Some  of  them  afford  good 
free  stones,  for  building,  whet-stones,  grind-stones, 
flagging-stones,  dec.  The  shale,  or  slate  clay,  differs 
from  clay-slate,  in  being  more  tender,  and  often  con- 
taining the  impressions  of  vegetables. 

An  ore  of  iron,  called  clay  iron  stone,  is  almost 
constantly  found  in  the  shale  of  the  coal  measures, 
either  in  distinct  layers,  or  in  courses  of  nodules. 
The  occurrence  of  this,  the  most  useful  of  the  metals, 
directly  associated  with  the  combustible  and  flux 
necessary  to  reduce  it,  is  an  instance  of  arrange- 
ment happily  adapted  to  the  purposes  of  human  in- 
dustry, and  is  one  of  the  proofs  that  the  distribution 
of  the  rude  materials  of  the  earth,  was  determined 
with  a  view  to  the  convenience  of  its  inhabitants.  * 

No  well  marked  line  of  distinction  can  be  drawn, 


What  are  the  most  important  rock  formations  in  these  di- 
visions ?  What  are  the  coal  measures  ?  For  what  are  some 
of  the  sandstones  of  the  coal  measures  used  ?  How  does 
shale,  or  slate  clay,  differ  from  clay  slate  ?  What  ore  of  iron 
occurs  in  the  coal  measures  ?  What  difference  is  there  in 
the  fossils  of  the  lower  secondary,  and  the  transition  rocks  ? 


106  SECONDARY  ROCKS. 

in  the  appearance  of  the  rocks  between  the  lower 
secondary  and  transition,  but  there  is  a  remarkable 
difference  in  the  nature  of  the  fossil  remains,  that 
serves  as  a  distinction.  In  the  transition,  it  was 
remarked  that  the  fossils  were  mostly  the  remains 
of  animals,  either  coralline  or  testaceous.  In  the 
lower  secondary,  the  remains  of  plants  are  most 
numerous,  and  they  are  analagous  to  those  growing 
in  tropical  climates. 

The  coal  fossils  of  Newcastle  Liege,  Melville's 
Island,  and  Pennsylvania,  are  identical,  as  are  the 
trilobites  of  Dudley,  and  of  Trenton  Falls  ;  the  shells 
of  the  coral  ragg  of  England,  are  those  of  animals 
still  living  but  confined  to  tropical  seas ;  all  seems 
to  indicate  that  the  climate  of  the  earth  was  at  some 
remote  period  uniform  throughout  its  whole  extent, 
more  heated  than  the  most  torrid  regions  are  at  pre- 
sent, and  utterly  unfit  for  the  habitation  of  any  exist- 
ing varieties  of  the  human  race.  [Am.  Quarterly 
Review,  Vol.  vi.  p.  446.] 

The  strata  of  the  coal  formation  often  rest  uncon- 
formably  on  the  more  inclined  strata  below  them. 

The  coal  formation  is  somewhat  variable  in  posi- 
tion but  within  limits  which  are  easily  assigned. 
[Brongniart's  Remains.'] 

The  rocks  forming  the  coal  measures,  by  their 
appearance  indicate  an  origin  almost  entirely  me- 
chanical. The  coal  alone  by  its  nature,  its  homo- 
geneousness,  ij:s  breaking  into  rhombic  masses,  and 


In  what  places  are  the  fossils  identical  ?     What  does  this 
seem  to  indicate  ? 


SECONDARY  ROCKS.  107 

the  presence  of  some  crystalline  metallic  minerals, 
indicate  the  influence  of  chemical  action. 

The  strata  of  the  coal  formation  are  numerous, 
extensive,  and  parallel ;  but  they  are  often  bent,  in- 
dulating,  curved,  broken,  and  contorted  in  various 
ways.  The  coal  formation  is  often  intersected  by 
dykes,  and  faults,  which  have  separated  the  beds  of 
coal,  or  broken  the  strata  and  deranged  the  position 
to  such  a  degree,  as  to  render  it  difficult  to  find  it 
again  on  the  other  side  of  the  fault  or  dyke.  [ Brong- 
mart's  Remains.] 

The  strata  connected  with  the  coal,  bear  evidences 
in  some  instances  of  having  been  rapidly  deposited ; 
thus,  the  vertical  stems  of  plants  standing  in  their 
natural  position,  in  many  coal  mines,  and  the  rocks 
deposited  around  them  in  horizontal  or  slightly  in- 
clined strata.  The  stems  of  arborescent  plants,  2 
or  3  feet  in  diameter,  are  thus  found  piercing  through 
the  strata  many  feet. 

The  sand  and  mud  must  have  been  deposited 
within  a  comparatively  short  time  around  them,  else 
in  a  climate  such  as  that  in  which  these  plants  grew, 
they  would  have  decayed  and  left  no  indications  of 
their  existence.  [Vido  Am.  des  Mines,  1821.] 

"  About  2  miles  above  Galliopolis,  and  half  a  mile  . 
from  the  Ohio  river  is  a  location  of  several  petrified 
trees." 
.  They  are  imbedded  in  a  coarse  sandstone  belong. 


What  facts  respecting  coal  indicate,  the  influence  of  chemi- 
cal action  ?  What  of  the  strata  of  the  coal  formation  ?  What 
are  the  evidences  that  the  strata  connected  with  the  coal  in 
some  instances  have  been  rapidly  deposited  ?  Where  have 
fossil  trees  been  discovered  ?  What  is  said  of  them  ? 


108  SECONDAKY  ROCKS. 

ing  to  the  coal  formation,  near  the  foot  of  a  mural 
precipice  of  50  to  70  feet  in  height,  a  few  feet  above 
the  foot  of  the  cliff.  The  trees  observed  were  7  in 
number,  and  are  scattered  through  a  space  quarter 
of  a  mile  in  length.  "  Some  appear  to  have  fallen,  or 
been  deposited  with  their  tops  or  branches  towards 
the  river ;  and  others  in  the  opposite  direction. — 
Some  project  from  the  rock  obliquely,  and  others  at 
right  angles ;  they  vary  from  8  to  18  inches  in 
diameter."  "They  are  readily  distinguished  from 
the  rock  in  which  they  are  imbedded  by  their  differ- 
ent  colour  and  composition." 

**  The  interstices  between  the  lamina?  are  in  some 
places  filled  with  small  crystals  of  quartz ;  and  in 
others  with  thin  layers  of  stone  coal."  "The  cor- 
tical  part  seems  to  have  been  more  difficult  to  pe- 
trify than  the  ligneous  portions."  The  bark  of  the 
tree  easily  separates  from  the  trunk,  and  is  in  some 
cases  coloured  with  oxide  of  iron,  and  in  others  is 
black  and  fragile  easily  crumbling  to  pieces.  [Hil- 
dreth  Am.  Journal,  xii.  p.  205.] 

Coal  occurs  in  regular  strata,  which  vary  in  thick- 
ness  from  a  few  inches  to  several  feet  or  even  yards. 
In  the  same  coal  formation,  many  strata  of  coal 
occur  under  each  other,  separated  by  strata  of  shale, 
sandstone,  &c. 

The  series  of  strata  which  occur  together,  is 
called  a  coal  field.  "  Coal  fields  are  of  limited  ex- 
tent, and  the  strata  often  dip  to  a  common  centres, 
being  often  arranged  in  basin  shaped  cavities,  which 
appear  to  have  been  originally  detached  lakes  that 

Bo  many  strata  of  coal  occur  in  the  same  coal  field,  amd 
how  are  they  arranged  ? 


SECONDARY  ROCKS.  109 

were  gradually  filled  by  repeated  depositions  of  car- 
bonaceous and  mineral  Sandstone.  Bv^pT^^ 
matter.'5  Slate. 

The  different  strata  Co^ 
over  and  under  the  beds  Slate. 
of  coal  are  frequently  Sandstone.  :'jjj$. 

similar,  and  the  same  se-     giate. 
ries  of  strata  is  repeated     ^oal 
for  each  successive  stra-     Slate  &c 
turn  of  coal,  thus —  IPHplB^^ 

Sometimes   the   strata  *&#&88$$$$i 

between  the  succeeding  beds  of  coal,  are,  in  the  ag- 
gregate, of  several  hundred  feet  in  thickness,  but 
often,  they  are  not  many  feet  thick,  and  sometimes 
only  a  few  inches.  In  the  latter  case,  the  adjacent 
beds  are  considered  as  one,  and  wrought  as  one  bed. 
The  stratum  over  the  bed  of  coal  is  called  the  roof, 
and  that  under  it,  the  floor.  Sometimes  there  are 
as  many  as  forty  distinct  beds  of  coal  below  each 
other  in  the  same  coal  field,  but  in  general,  only  a 
few  are  of  sufficient  thickness,  or  of  a  proper  quality, 
to  afford  profit  in  working. 

The  facility  of  getting  coal  depends  very  much 
upon  the  strength  of  the  roof,  and  the  impermeabil- 
ity of  the  rock  to  water.  At  Newcastle,  in  Eng- 
land, coal  is  wrought  at  the  depth  of  fifteen  hundred 
feet,  and  has  been  found  there  by  boring,  at  the 
depth  of  three  thousand  feet. 

There  has  been  some  disagreement  as  to  the 
origin  of  coal,  upon  the  ground  that  if  we  admit  its 


Upon  what  does  the  facility  of  working  coal  depend  ? 
10 


110  SECONDARY  ROCKS. 

vegetable  origin,  we  are  bound  by  similar  reasoning 
to  admit  that  the  limestones  containing  organic  re- 
mains are  animal  deposites,  arising  from  the  suc- 
cessive growth  and  death  of  myriads  of  animated 
beings,  and  few  are  willing  to  admit  that  the  enor- 
mous masses  of  rock,  often  some  hundreds  of  miles 
in  length  and  breadth,  and  many  hundreds  of  feet 
in  thickness,  can  have  arisen  from  such  a  source, 
notwithstanding  the  evidence  afforded  by  their  nu- 
merous remains. 

Such  need  only  glance  at  the  effects  of  the  com- 
bined labours  of  successive  races  of  millions  of  mil- 
lions of  polypi,  in  the  formation  of  the  extensive  reefs 
of  coral,  which  obstruct  the  navigation  of  many  parts 
of  the  Pacific  and  Indian  oceans. 

The  abundance  of  vegetable  remains  usually  found 
in  connection  with  coal,  and  the  vegetable  structure 
that  the  coal  itself  sometimes  exhibits,  will  hardly 
allow  a  doubt  as  to  its  origin. 

At  most  coal  mines  even  the  thinnest  layers  of 
slate,  when  split  off,  show  the  impressions  of  the 
leaves  and  flat  stems  of  the  various  grasses,  reeds 
and  ferns,  in  all  their  most  delicate  parts.  The  im- 
pressions between  the  layers  of  slate  often  give  as 
perfect  a  representation  of  the  plant,  as  if  the  plant 
had  been  pressed  and  dried  in  a  book,  and  the  leaves 
then  opened  to  display  it. 

"  Whatever  may  have  been  the  origin  of  coal,  we 
cannot  hesitate  in  admitting  that  vegetable  life  on  a 
great  scale,  attended  the  formation  of  coal,  and  both 
preceded,  accompanied,  and  followed,  that  event ; 


What  is  supoosed  to  be  the  origin  of  coal  ? 


SECONDARY  HOCKS.  Ill 

and  that  the  causes  which  established  its  existence, 
were  repeated  many  times,"  at  considerable  inter- 
vals of  time,  and  continued  to  operate  during  the  de- 
position of  the  successive  strata :  that  a  sedimentary 
rock  in  a  loose  and  impressible  form,  (the  shale,) 
was  deposited  with  the  vegetables,  and  enveloped, 
covered,  and  preserved  them ;  that  a  fragmentary 
rock  succeeded,  composed  of  pebbles,  rounded  or  an- 
gular fragments,  or  of  cemented  sand,  which  were  the 
ruins  of  pre-existing  formations.  [Silliman's  Jour- 
nal, xviii.  p.  321.] 

Coal  and  the  accompanying  strata  usually  lie 
parallel  to  each  other,  like  the  leaves  of  a  book,  and 
incline  under  a  small  angle  to  the  horizon,  so  that 
the  strata  would  emerge  on  the      ffT/7j/7i 
surface,  thus.     It  is  rare  that  the    ///////// 
coal,  or  shale,  crop  out  on  the  sur-     \f*-i<ff*Jf  „ 
face,  because  a  diluvial  or  alluvial  covering  usually 
conceals  the  outcrop,  except  in  the  sides  of  ravines, 
the  banks  of  streams,  or  the  faces  of  cliffs.     "  The 
rock  strata  are  in  geology,  what  the  bones  are  in 
anatomy,  when  the  covering  is  once  removed,  the 
absolute    structure   is   at   once   seen."      \Eatotfs 
Geology. ,] 

In  searching  for  coal,  observe  the  kinds  of  rock, 
loose  stones,  and  pebbles,  examine  the  springs  and 
beds  of  streams  for  sooty  matter,  and  trace  it  as  near 
as  possible  to  whence  it  issued  ;  ascertain  the  direc- 
tion of  the  dip,  then  bore  in  a  proper  situation,  and 


Do  the  coal  strata  generally  crop  out  on  the  surface  ?     In 
searching  for  coal,  how  would  you  proceed  ? 


112  SECONDARY  ROCKS. 

'  ascertain  the  quality  and  thickness  of  the  bed,  and 
whether  there  be  more  than  one  bed. 

Coal  exists  very  abundantly  in  the  United  States, 
and  it  is  in  general  very  conveniently  situated  for 
working  to  advantage.  The  coal  mines  of  Virginia 
and  Pennsylvania  are  more  extensively  wrought 
than  any  others  in  the  United  States,  and  the  quan- 
tity seems  perfectly  inexhaustible. 

In  Europe,  where  the  people  are  mostly  dependent 
upon  the  produce  of  their  coal  mines  for  fuel,  the 
coal  mines  are  extensively  wrought,  and  under  cir- 
cumstances that  require  all  the  aid  that  the  sciences 
yield.  There  are  more  hazards  to  encounter,  and 
difficulties  to  overcome,  in  working  coal  mines  than 
any  other. 

The  coal  formation  which  has  been  described,  is 
the  great  or  independent  coal  formation,  and  is  sup- 
posed to  be  the  principal  repository  of  carbonaceous 
matter  applicable  to  use.  This  coal  is  the  bitumi- 
nous coal,  called  also  sea-coal,  black-coal,  caking- 
coal,  &e.  It  gives  much  smoke  when  burning. 

It  has  generally  been  thought  that  the  anthracite 
coal9  of  Pennsylvania,  belonged  to  the  transition 
rocks ;  but  Prof.  Eaton  thinks  he  has  traced  its  con- 
nection with  the  Tioga  bituminous  coal,  and  the  or- 
ganic remains  are  many  of  them  similar  to  those  of 
the  great  coal  formation.  It  would  seem,  then,  that 


Is  coal  abundant  in  the  United  States  ?  and  where  are  the 
mines  wrought  most  extensively  ?  Are  there  many  difficul- 
ties in  working  coal  mines  ?  What  coal  formation  is  that 
which  has  been  described,  and  what  are  the  names  of  the 
coal  ?  Does  the  anthracite  of  Pennsylvania  seem  to  have 
the  same  geological  position  as  the  great  coal  formation  ? 


SECONDARY  ROCKS.  113 

the  anthracite  of  Pennsylvania  belongs  to  the  great 
coal  formation. 

There  is  another  species  of  coal,  occurring  in  a 
different  geological  position  from  either  of  the  others, 
and  is  called  wood  coal  and  lignite,  from  its  showing 
distinctly  that  it  has  been  formed  from  wood.  It  is 
often  found  in  the  form  of  trees,  branches  and  fruits, 
and  still  retaining  the  appearance  of  the  wood,  ex- 
cept the  colour.  "  Wood  coal  is  found  in  low  situa- 
tions, and  appears  to  have  been  formed  of  heaps  of 
trees,  buried  by  inundations  under  beds  of  clay,  sand 
or  gravel."  "In  wood  coal  we  may  almost  seize 
nature  in  the  act  of  making  coal,  before  the  process 
is  completed.  These  formations  of  coal  are  of  far 
more  recent  date  than  that  of  common  coal,  though 
their  origin  must  be  referred  to  a  former  condition 
of  the  globe,  when  the  vegetable  productions  of  tro- 
pical climates  flourished  in  northern  latitudes." 

Jet,  which  is  used  as  an  ornament,  is  a  variety  of 
lignite  which  has  lost  its  ligneous  structure.  Am- 
ber is  generally  found  with  lignite,  and  appears  to 
have  been  a  resinous  substance  that  exuded  from 
the  wood,  and  has  become  changed  by  being  so  long 
imbedded  in  the  earth.  Amber  often  contains  fn- 
sects  imbedded,  which  shows  that  it  must  have  been  ^ 
in  a  soft  state,  and  on  the  earth's  surface,  and  in  * 


Is  there  any  other  kind  of  coal,  and  having  a  different 
geological  position  ?  What  is  it  called  ?  and  from  what  cir- 
cumstance? Which  coal  is  of  the  most  recent  origin? 
What  kind  of  plants  flourished  when  this  coal  was  deposited  ? 
What  is  jet  ?  In  what  situation  is  amber  found  ?  What 
appears  to  have  been  its  origin  ?  What  does  amber  often 
contain  ? 

10* 


114         UPPER  SECONDARY  ROCKS. 

which  they  became  entangled,  as  they  do  now  in 
the  gums  and  resins  that  exude  from  certain  trees. 
They  may  be  often  observed  in  gum  copal  beauti- 
fully preserved. 

Lignite  occurs  in  large  quantities  in  New  Jersey, 
along  Raritan  Bay,  in  the  cliffs,  and  in  various  other 
parts  of  the  country.  The  large  bodies  of  the  plants 

<^ *a    are  generally  flattened,  (as  seen  in  the 

margin,)  as  though  the  weight  of  the  su- 
perincumbent earth  had  pressed  the  sides  together. 


CHAPTER  VIII. 
UPPER   SECONDARY   ROCKS. 

The  upper  secondary  rocks  comprise  all  the  dif- 
ferent formations  above  the  great  coal  formation,  to 
the  upper  limit  of  the  chalk  series.  These  rocks 
are  divided  into  3  formations,  viz  : 

1.  CHALK,  or  cretaceous  rocks,  including  the  fer- 
ruginous and  green  sand ; 

2.  OOLITIC  ROCKS,  lias  limestone  and  lias  clay ; 

What  does  this  show?  In  what  may  insects  be  observed 
beautifully  preserved?  Does  lignite  occur  in  the  United 
States?  How  do  the  bodies  of  the  large  plants  appear? 
What  seems  to  have  caused  this  flattening  ?  What  are  the 
limits  of  the  upper  secondary  rocks  ?  Into  what  formations 
are  they  divided  ? 


UPPER  SECONDARY  ROCKS.         115 

3.  RED  SANDSTONE,  including  magnesian  lime- 
stone. 

The  red  sandstone  goes  also  by  the  names  of  va- 
riegated sandstone,  new  red  sandstone,  and  red  marl ; 
and  is  most  important  as  being  the  principal  reposi- 
tory of  rock  salt.  The  magnesian  limestone  is  the 
lowest  part  of  this  rock  formation,*  This  limestone 
dissolves  more  slowly  than  other  limestone,  and  is 
generally  of  a  buff  colour,  and  sandy  in  its  texture. 
Some  of  these  limestones  form  an  excellent  building 
material,  and  yield  a  fetid  smell  when  hammered. 
They  make  a  good  lime  for  cements,  but  it  will  not 
answer  for  liming  land,  as  it  injures  the  fertility  of 
the  soil.  Magnesia  is  found  to  be  uniformly  injuri- 
ous to  vegetation,  and  magnesian  soils  are  barren. 
The  fossils  in  this  limestone  are  not  numerous. 

The  texture  of  the  rocks  of  the  red  sandstone  for- 
mation is  very  various.  It  appears  sometimes  as  a 
reddish  marl  or  clay,  sometimes  as  a  sandstone,  and 
sometimes  these  are  interstratified,  or  pass  into  each 
other,  and  it  is  sometimes  associated  with  beds  of  a 
conglomerate  rock,  which  is  composed  of  pebbles 
and  fragments  of  other  rocks  cemented  together. 

The  soil  where  this  formation  occurs  is  reddish, 
and  sheep  living  on  it  have  their  wool  tinged  with 
red. 

There  is  often  a  strong  similarity  between  the 
sandstone  of  the  coal  measures,  and  that  of  this  for- 


For  what  is  the  red  sandstone  most  important  ?  What 
are  the  characters  of  magnesian  limestone  ?  What  are  the 
characters  of  the  red  sandstone  formation  ?  What  is  the 
colour  of  the  soil  of  this  formation  ? 


116         UPPER  SECONDARY  ROCKS. 

mation,  but  they  may  be  distinguished  by  the  latter 
containing  gypsum. 

The  red  sandstone  formation  is  characterized  by 
the  first  appearance  of  any  abundance  of  the  remains 
of  the  saurian,  or  lizard-shaped  animals.  The  re- 
mains  of  a  number  of  species  have  been  found,  dif- 
fering in  their  appearance  from  the  crocodile  and 
alligator,  and  some  of  them  must  have  been  from  60 
to  120  feet  in  length. 

These  animals  appear  to  have  lived  in  salt  water, 
unlike  any  of  this  class  with  which  we  are  acquaint- 
ed at  the  present  (jay,  all  of  which  belong  either  to 
the  land,  or  to  fresh  water.  They  had  neither  feet 
nor  fins,  but  paddles,  like  the  sea-turtle,  and  their 
tails  were  long,  of  the  form  of  an  oar,  and  fitted  to 
propel  them  in  the  most  agitated  waters,* 

The  most  valuable  minerals  found  in  the  red  sand- 
stone are,  gypsum  and  rock  salt.  The  gypsum  is 
fibrous,  massive,  and  crystallized.  Many  reposito- 
ries of  rock  salt  are  situated  near  the  foot  of  moun- 
tain ranges,  and  although  salt  is  more  frequently 
found  at  a  comparatively  low  level,  it  has  also  been 


How  are  the  sandstones  of  this  and  the  coal  formation  dis- 
tinguished ?  By  what  organic  remains  is  the  red  sandstone 
characterized  ?  What  appears  to  have  been  the  size  of  those 
animals  ?  Where  do  they  appear  to  have  lived  ?  Had  they 
feet,  or  fins  ?  Were  they  calculated  for  moving  on  land,  or 
in  the  water  ?  What  are  the  most  valuable  minerals  found 
in  the  red  sandstone  ?  How  is  rock  salt  situated  ?  Does  it 
ever  form  extensive  masses  ? 

*  Fish  are  common  in  a  bi  turn  in  on  s  marly  state  belonging  to  this 
formation  in  Europe,  and  also  in  the  U.  S.,  as  Sunderland  Mass.,  Mid- 
dletown,  and  Durliam,  Conn. 


UPPER  SECONDARY  ROCKS.          117 

found  high  above  the  level  of  the  sea,  as  in  the  Alps, 
and  on  the  Andes. 

The  great  salt  mines  of  Cheshire,  in  England,  of 
Wielictska,  in  Poland,  and  those  in  Germany,  Spain, 
Russia  and  Turkey,  are  in  the  red  sandstone  forma- 
tion. The  salt  of  Cardona,  in  Spain,  appears  to 
have  been  an  enormous  mass,  in  which  the  water 
has  formed  vallies,  "  leaving  several  detached  moun- 
tains."—[S.  J.  xv.  p.  1,  2.] 

*'  Nothing  can  compare  with  the  magnificence  of 
the  spectacle  which  the  mountain  of  Cardona  ex- 
hibits at  sunrise.  Besides  the  beautiful  forms  which 
it  presents,  it  appears  to  rise  above  the  river  like  a 
mountain  of  precious  gems,  displaying  the  various 
colours  produced  by  the  refraction  of  the  solar  rays 
through  a  prism."  [Bakewell,  p.  187.] 

Hungary  and  Poland  afford  the  most  numerous 
and  extensive  repositories  of  rock  salt  in  Europe. 

There  is  a  formation  of  rock  salt  on  each  side  of  the 
Carpathian  mountains,  six  hundred  miles  in  length. 

"  The  salt  mines  of  Welielska,  near  Cracow,  have 
been  long  celebrated,  and  frequently  described : 
they  are  worked  at  the  depth  of  750  feet."  "At 
Paraid,  in  Transylvania,  there  is  a  valley,  the  bot- 
tom and  sides  of  which  are  pure  rock  salt.  The 
mine  of  E  per  is  is  about  990  feet  deep.  Water  is 
sometimes  enclosed  in  blocks  of  salt." — [Brongniart, 
Miner  alogie.~\ 

On  the  northern  shore  of  Africa,  not  far  from  Al- 
giers and  Tunis,  are  salt  lakes,  communicating  with 


In  what  parts  of  Europe  is  rock  salt  found  abundantly  ? 
How  is  rock  salt  found  in  lakes  in  Africa  ? 


118         UPPER  SECONDARY  ROCKS. 

the  Mediterranean  Sea  by  small  openings,  through 
which,  during  the  warm  season,  there  is  a  continual 
influx  of  the  salt  water,  and  from  the  deposit  of  salt, 
consequent  upon  the  evaporation  of  the  water,  some 
of  them  have  become  shallow,  and  their  bottoms 
covered  to  an  unknown  depth  with  rock  salt.  Some 
of  the  salt  lakes  of  Africa  dry  up  entirely  in  the 
summer,  and  leave  a  bed  of  pure  rock  salt. 

The  salt  lakes  of  Africa,  on  the  borders  of  Caf- 
fraria,  east  of  the  Cape  of  Good  Hope,  contain  beds 
of  rock  salt  variously  coloured.  There  is  a  re- 
markable  formation  of  salt  at  Posa,  in  Castile, 
placed  in  the  immense  crater  of  an  extinct  volcano. 

The  salt  of  Northwich  (Cheshire  Co.  England) 
alternates  with  clay,  and  marl  containing  gypsum. 
The  upper  bed  of  salt  is  from  60  to  90  feet  thick, 
and  below  this,  separated  by  a  bed  of  clay,  is  ano- 
ther which  has  been  penetrated  108  feet  without 
finding  its  bottom.  This  mine  yields  156,000  tons 
of  salt  per  annum.  The  mines  and  springs  of  salt 
in  Europe  yield  15,000,000  tons  of  salt  per  annum. 

Rock  salt  has  not  been  found  in  the  United  States, 
except  far  to  the  west  of  the  Mississippi.  "  The  salt 
mountain  is  situated  at  the  head  of  one  of  the  western 
branches  of  the  Arkansas."  [StoddarcPs  Sketches, 
p.  403.] 

Salt  springs  are  very  numerous  in  many  parts  of 
the  United  States.  The  water  sometimes  flows  na- 


Has  rock  salt  been  found  in  the  United  States  ?  Are  salt 
springs  numerous  in  the  United  States  ?  How  is  the  salt  wa- 
ter more  frequently  obtained  than  from  the  natural  springs 
upon  the  surface  ? 


UPPER  SECONDARY  ROCKS.          119 

turally,  but  more  frequently  it  is  obtained  by  boring 
through  the  strata  where  salt  water  is  known  to 
exist,  in  the  vicinity  of  salt  licks.*  These  licks 
were  the  places  of  resort  for  wild  animals  before  the 
settlement  of  the  country.  They  were  easily  found 
when  the  country  was  newly  settled,  by  the  paths 
which  converged  from  various  directions  to  the  licks, 
where  the  animals  repaired  to  lick  the  clay  impreg- 
nated with  salt. 

Some  of  these  licks  are  remarkable  for  the  quan- 
tities of  fossil  bones  found  adjacent  to  them.  The 
bones  of  the  Mastodon,  the  Elephant,  &c.,  are  most 
abundant,  and  the  lick  called  Big  Bone  Lick,  in 
Kentucky,  is  the  one  at  which  these  remains  have 
been  found  in  the  greatest  abundance. 

The  Mastodon  was  the  largest  land  animal  that  is 
known  to  have  existed.  This  animal,  which  is  not 
in  existence  at  present,  was  formed  much  like  the 
elephant,  except  in  the  teeth  ;  but  the  elephant  must 
have  seemed  a  pigmy  by  his  side.  The  teeth  of  the 
great  Mastodon  often  weigh  from  six  to  seven  pounds 
each,  and  one  of  the  tusks  is  as  much  as  a  strong 
man  can  lift. 

As  to  the  origin  of  salt  deposits,  and  salt  springs, 
many  opinions  have  been  advanced.  Rock  salt  is 
________  * 

What  are  salt  licks  ?  For  what  are  some  of  these  remark- 
able  ?  Which  of  these  licks  has  the  greatest  number  of  those 
fossil  bones?  Of  what  animals  are  the  remains  most  com- 
mon ?  What  is  said  of  this  animal  ?  Upon  what  are  all 
agreed  in  the  deposition  of  rock  salt  ? 

*  It  is  necessary  to  drill,  or  bore  through  rocks,  often  several  hun- 
dred feet,  before  the  salt  water  is  reached,,  and  then  the  water  rises, 
and  overflows  at  the  surface. 


120          UPPER  SECONDARY  ROCKS. 

usually  of  a  crystalline  texture,  and  is  associated 
with  materials  that  have  evidently  been  subjected  to 
the  action  of  water,  as  clays  and  sands,  and  con- 
glomerates of  sand,  gravel,  pebbles,  &c.,  and  these 
often  contain  shells,  and  the  teeth  and  bones  of  ma- 
rine animals. 

All  agree,  that  the  salt  deposits  bear  conclusive 
evidence  of  having  been  deposited  from  water. 

Salt  springs,  in  Europe,  are  most  abundant  where 
rock  salt  abounds,  and  from  flowing  over  its  beds, 
the  water  is  doubtless  impregnated.  This  explana- 
tion will  not  hold  for  our  salt  springs,  for,  rock  salt, 
although  it  has  been  diligently  sought  for  in  the 
vicinity  of  salt  springs  in  this  country,  has  not  been 
found. 

Prof.  Eaton  has  published  a  fact  that  goes  far  to 
prove  its  origin.  He  mentions,  that  fragments  of 
the  hydraulic  limestone,  found  a  few  miles  west  of 
the  Onondaga  salt  springs,  when  examined  exter- 
nally, or  pulverized,  presents  nothing  to  the  senses 
resembling  common  salt,  but  when  kept  a  few  days 
in  a  moist  cellar  they  became  incrusted  with  com- 
mon  salt.-— [S.  J.  vi.  p.  242.] 

He  has  also  found  in  some  of  the  rocks,  cubic 
cavities,  and  cavities  like  the  hopper-shaped  crystals 
of  common  salt.  Although  several  minerals  crystal- 
lize in  the  cubic  form,  none  but  salt  are  known  to 
have  the  hopper-shaped  form. 

These  facts  constitute  a  train  of  evidence,  which 


Will  the  same  explanation  hold  for  our  salt  springs,  as  for 
those  of  Europe  ?  From  what  is  it  probable  that  the  salt  of 
our  salt  springs  is  derived  ? 


LIAS.  121 

renders  it  probable,  that  the  salt  of  the  salt  springs, 
is  derived  either  from  salt,  or  its  elements,  contained 
in  the  rocks  overlying  that,  on  which,  as  a  floor,  all 
the  salt  springs  are  found. 

It  is  a  fact  worthy  of  remark,  that  salt,  a  min- 
eral so  necessary  to  supply  the  wants  of  man,  is 
found  abundantly  in  almost  every  country,  either  in 
its  solid  state,  or  dissolved  in  the  water  of  springs. 
Denmark,  Sweden,  and  the  eastern  part  of  the  United 
States,  are  exceptions,  but  they  are  placed  in  such  a 
situation  that  they  can  easily  draw  their  supplies 
from  the  great  reservoir  of  this  mineral,  the  ocean. 

LIAS. 

The  lias  limestone  and  clay,  when  fully  developed, 
form  a  mass  of  several  hundred  feet  in  thickness, 
lying  upon  the  red  sandstone  formation. 

The  limestone  is  of  a  bluish  or  light  buff  colour, 
and  very  compact.  It  often  contains  bitumen,  alu- 
mina, and  oxide  of  iron.  The  finer  kinds  of  lias 
limestones  receive  a  polish,  and  are  used  for  lithog- 
raphy. The  lithographic  stone  to  be  well  adapted 
for  this  use  should  be  very  compact ;  have  a  very 
fine  grained  uneven  conchoidal  fracture ;  should 
contain  some  earthy  matter  insoluble  in  nitric  acid? 
and  if  the  stone  is  light  coloured  it  is  better,  as  the 


Is  salt  found  abundantly  in  every  country  ?  Whence  do 
people  draw  their  supplies  of  salt,  when  they  have  neither 
rock  salt  nor  salt  springs  ?  Upon  what  does  the  lias  lie  ? 
What  are  the  characters  of  the  lias  limestone  ?  For  what  is 
it  employed  ?  What  qualities  should  the  lithographic  stone 

11 


122  LIAS. 

drawings  can  be  done  more  accurately  than  on  a 
darker  ground. 

The  quarries  of  Pappenheim,  and  Solenhofen, 
near  Eichstaedt  in  Bavaria,  supply  almost  all  the 
stone  used  for  lithography.  The  quarries  above 
mentioned  supply  the  cabinets  of  geology  with  many 
beautiful  specimens  of  fossil  fish  imbedded  in  the 
limestone.  This  limestone  is  also  employed  for 
making  hydraulic  cement. 

The  lias  is  beautifully  stratified  in  regular  layers 
which,  in  most  places  where  it  has  been  observed, 
are  horizontal.  It  derives  its  name  from  a  provin- 
cial pronunciation  of  the  word  layers.  It  is  charac- 
terized by  its  numerous  and  finely  preserved  fossils. 
The  most  remarkable  of  the  fossils  are  fishes,  and 
the  large  saurian  animals  called  the  ichthyosaurus, 
and  plesiosaurus. 

Some  idea  of  the  magnitude  of  some  of  these  ani- 
mals may  be  formed  from  the  fact,  that  the  orbits 
for  the  eyes  of  some  of  these  animals  are  9  and  10 
inches  in  diameter.  The  lias  clay  occupies  the 
upper,  and  the  limestone  the  lower  parts  of  the  for- 
mation. Bones  and  other  organic  matter  can  be 
rapidly  petrified  in  the  pyritous  lias  clay. 

The  lias  clay  often  occurs  in  the  form  of  a  soft 
clay  or  shale,  impregnated  with  pyrites  and  bitumen. 
When  made  red  hot,  if  more  be  piled  on  the  first, 


Where  is  it  chiefly  obtained  ?  From  what  does  lias  de- 
rive its  name  ?  What  are  the  most  remarkable  of  the  fossils 
of  the  lias  ?  What  position  does  the  lias  clay  occupy  in  the 
formation  ?  What  the  limestone  ?  How  does  the  lias  clay 
appear  ?  Can  it  be  made  to  burn  ? 


OOLITE.  123 

it  also  ignites,  and  continues  to  burn  gradually  for 
some  time.  In  this  way,  immense  heaps  of  this  ma- 
terial, called  alurn  slate,  are  roasted,  and  prepared 
for  making  alum.* 

OOLITE. 

The  oolitic  rocks  are  composed  o£  various  strata 
of  limestone,  clay,  sand  and  sandstone.  Oolite  de- 
rives its  name  from  the  small  globules  that  are  im- 
bedded in  the  rock,  and  some  of  the  masses  appear 
composed  of  little  rounded  globules  like  the  roes  of 
fish,  from  which  it  is  also  called  roe  stone. 

Limestone  rocks  having  an  oolitic  structure  have 
been  found  in  many  places  in  the  United  States ; 
but  they  have  not  been  shown  as  equivalents  to  the 
European  oolite,  either  by  there  position  or  organic 
remains. 

r  Warwick,  N.  Y. 
J  Saratoga,       " 
Localities.  <  Schoharrie,   " 

Easton,  Pa. 
I  Franklin,  N.  J. 


What  is  made  from  it  after  it  has  been  burnt  ?  How  is 
alum  m  ade  ?  Of  what  are  the  oolitic  rocks  composed  ?  From 
what  does  oolite  derive  its  name  ?  In  what  places  in  th£ 
United  States  has  limestone  rock  of  oolitic  structure  been 
found? 

*  Alum  is  composed  of  sulphuric  acid,  alumina,  and  potassa.  The 
sulphur  of  the  pyrites  in  the  clay,  forms  a  sulphuric  acid  during  the 
burning,  which  unites  with  the  alumina  and  potossa  in  the  clay,  and 
forms  alurn.  By  leaching  water  through  the  burnt  clay,  and  evapo- 
rating the  water,  alum  is  obtained.  Sometimes  the  clay  does  not 
contain  potassa,  and  then  that  is  supplied  by  mixing  common  wood 
ashes  with  the  burnt  clay,  and  leaching  and  evaporating  the  water  as 
before. 


124  OOLITE. 

This  limestone  is  sometimes  employed  as  a  build- 
ing stone,  but  it  is  not  durable.  The  oolitic  rocks 
are  remarkable  for  the  great  variety  of  organic  re- 
mains contained  in  them.  "  The  vertebrated  ani- 
mals, whose  remains  are  found  in  oolite,  are  some  of 
them  of  the  same  genera  as  those  discovered  in  lias  ; 
but  others  belojyg  to  the  crocodile  genus,  and  had 
feet,  like  the  living  species  of  crocodile,  and  were 
probably  amphibious  :*  hence  we  may  infer,  that 
that  there  were  rivers  and  dry  land  in  the  vicinity." 

"It  may  well  excite  surprise,  that  calcareous 
strata  should  so  rarely  be  found  which  present  dis- 
tinct indications  of  having  been  formed  exclusively 
by  coralline  polypi,  particularly  as  coral  rocks  and 
reefs  of  great  extent  are  so  rapidly  forming  in  our 
present  seas.  There  are,  however,  among  the  strata 
of  oolite,  some  which  are  almost  entirely  composed 
of  madreporites,  and  have  received  the  name  of  coral 
ragg.  There  are  other  strata  which  abound  in  the 
remains  of  fossil  sponges,  alcyonia,  and  with  con- 
geries of  minute  millepores  and  madrepores." — 
[BakeweWs  Geology,  p.  201.] 

Between  the  oolite  and  chalk,  a  formation  of  limit- 
ed extent  has  been  found  in  England,  called  the 
Wealden  rocks.  The  different  strata  are  called 


For  what  are  these  rocks  remarkable  ?  Are  there  any 
rocks  formed  by  the  coralline  polypi  among  the  oolitic  strata  ? 
What  are  they  called  ?  Are  any  filled  with  fossil  sponges  ? 
What  are  the  different  strata  of  the  wealden  rocks  called  ? 

*  These  were  the  ichthyosauri.  The  plesiosauri  had  long  arched 
necks  longer  than  the  body,  which  were  adapted  like  that  of  the  tes- 
tndo  ferox  for  darting  forward  to  seize  its  prey. 


OOLITE.  125 

purbeck  beds,  iron  sand,  weald  clay,  and  green 
sand. 

The  animal  remains  are  those  belonging  to  the 
land,  and  to  fresh  water.  The  teeth  and  bones  of 
fish  and  reptiles  are  abundant,  and  intermixed  with 
fresh  water  shells.  The  reptiles  are  mostly  saurian 
animals,  and  turtles.  The  plesiosaurus,  megalosau- 
rus,  and  iguanodon  are  among  them ;  and  some  of 
them  must  have  been  70  feet  in  length,  and  of  the 
height  of  an  elephant.  The  iguanodon  resembled 
the  iguana  of  the  West  Indies  in  some  of  its  charac- 
ters, but  its  teeth  are  similar  to  those  of  herbiferous 
mammalia,  which  grind  their  food  between  them, 
like  the  horse  and  ox.  Its  length  was  between  60 
and  70  feet,  and  it  had  a  horn  in  size  and  form  re- 
sembling that  of  the  rhinoceros.  It  seems  to  have 
been  fitted  for  subsisting  on  the  hard  coarse  plants 
which  prevailed  at  this  period. 

The  vegetable  fossils  in  these  rocks  consist  of  the 
trunks  of  palms,  arborescent  ferns,  and  gigantic 
reeds,  and  similar  ones  now  grow  only  in  tropical 
climates. 

In  one  of  the  rocks  belonging  to  the  oolite,  viz : 
the  stonesfield  slate,  the  earliest  remains  of  mammif- 
erous  animals  were  observed.  They  are  stated  by 
Cuvier  to  belong  to  an  extinct  species  of  the  opos- 
sum. Animals  belonging  to  this  order,  are  now 
found  only  in  America,  and  New  Holland. 


What  are  the  different  animal  remains  found  in  them  ? 
What  of  the  Iguanodon  ?  What  are  the  vegetable  fossils  of 
these  rocks  ?  In  what  have  the  earliest  remains  of  Mammif . 
erous  animals  been  found  ? 

11* 


126  CHALK. 

CHALK. 

The  cretaceous  rocks  or  those  belonging  to  the 
chalk  formation,  are  mostly  calcareous.  The  car- 
bonate of  lime  is  sometimes  very  pure  as  in  white 
chalk,  sometimes  mixed  with  clay  and  sand  to  form 
marl  of  various  colours,  as  white,  gray,  blue,  green, 
yellow,  and  black.  Sometimes  it  is  consolidated 
into  a  limestone,  and  is  used  for  building  and  mak- 
ing lime.  Some  of  the  beds  of  the  chalk  formation 
are  sandy. 

The  chalk  formation  is  entirely  sedimentary,  ap- 
pearing to  have  separated  from  suspension  in  wa- 
ter ;  and  it  shows  no  traces  of  crystallization,  ex- 
cept where  organic  remains  have  been  replaced  by 
carbonate  of  lime. 

The  stratification  is  often  indistinct,  and  it  then 
^'presents  itself  as  a  thick  mass  intersected  by  numer- 
ous fissures,  which  divide  the  mass  into  enormous 
irregular  masses.  If  the  seams  of  stratification  did 
not  indicate  clearly  a  successive  deposit  of  the  dif- 
ferent parts  of  the  formation,  the  flint  nodules  which 
occur  in  regular  parallel  beds  in  the  chalk,  would 
leave  no  doubt  on  this  point. 

The  chalk  formation  in  Europe,  presents  itself 
under  the  form  of  extensive  plains  with  steep  escar- 
pments on  the  sides,  or  round  backed  hills  of  little 


What  of  cretaceous  rocks  ?  What  of  carbonate  of  lime  ? 
What  distinguishes  the  chalk  formation  ?  What  appearance 
does  its  stratification  present  ?  What  is  the  proof  of  succes- 
sive deposit  of  this  formation  ?  How  does  the  chalk  forma- 
tion in  Europe  present  itself  ? 


CHALK.  127 

height  but  with  steep  declivities.  It  often  covers 
a  great  extent  of  country,  and  generally  contains 
neither  caverns  nor  currents  of  water,  but  large  open 
fiss-  :es  are  numerous. 

The  chalk  formation  has  not  been  recognized  in 
the  United  States  until  within  a  few  years.  Dr. 
S.  G.  Morton  of  Philadelphia  has  demonstrated  that 
a  chalk  formation  of  great  extent,  exists  in  the 
United  States ;  although  proper  mineralogical  chalk 
has  not  been  found. 

The  chalk  formation  is  characterized  by  particu- 
lar fossils.  The  fossils  of  the  chalk  are  very  nu- 
merous both  in  individuals  and  in  genera  and  species, 
but  they  are  very  unequally  distributed.  In  some 
districts  they  are  rare,  and  again  in  particular  lo- 
calities they  are  found  in  great  numbers. 

Mr.  Mantell  concludes  his  "  Illustrations  of  the 
geology  of  Sussex"  with  the  following  remarks : 
"  The  gigantic  Megalosaurus,  and  yet  more  gigantic 
Iguanodon,  to  whom  the  groves  of  palms  and  arbores- 
cent ferns  would  be  mere  beds  of  reeds,  must  have 
been  of  such  prodigious  magnitude,  that  the  existing 
animal  creation  presents  us  with  no  fit  objects  of 
comparison.  Imagine  an  animal  of  the  lizard  tribe 
three  or  four  times  as  large  as  the  largest  crocodile, 
having  jaws,  with  teeth  equal  in  size  to  the  incisors 
of  the  rhinoceros,  and  crested  with  horns  ; — such  a 
creature  must  have  been  the  Iguanodon  !  Nor  were 
the  inhabitants  of  the  waters  much  less  wonderful , 


Who  has  demonstrated  the  existence  of  the  chalk  forma- 
tion in  the  United  States  ? 


128  TERTIARY  ROCKS. 

witness  the  plesiosaurus,  which  only  required  wings 
to  be  a  flying  dragon  :  the  fishes  resembling  Siluri, 
Balistse,  &c." 


CHAPTER  IX. 
TERTIARY  ROCKS. 

The  tertiary  rocks  comprise  all  the  regular  beds 
of  limestone,  clay,  marl,  sandstone,  or  sand,  which 
were  deposited  since  chalk. 

The  tertiary  deposits  contain  no  beds  of  minerals 
capable  of  exploration  except  lignite  and  jet,  which 
are  used  for  fuel  and  ornament,  clay  for  pottery,  sand 
for  the  manufacture  of  glass,  pyrites  for  the  manufac- 
ture of  coperass  and  alum,  and  hydrate  of  iron, 
which  is  a  valuable  iron  ore.  The  pyrites  are  found 
only  in  detached  nodules  and  small  interrupted  beds. 

No  veins  either  strong  or  metallic  are  found  in 
the  tertiary. 

There  are  sometimes  fissures,  sinuous  passages, 
vertical  pits,  and  some  caverns  in  the  tertiary,  but 
they  are  rare. 

The  predominating  minerals  of  the  tertiary  are 
sand,  clay,  and  marl.  Sandstone,  gypsum,  lime- 
stone, and  buhrstone  are  sometimes  found.  Most 


What  do  the  tertiary  rocks  comprise?  What  minerals 
capable  of  exploration  are  contained  in  the  tertiary  deposits  ? 
What  are  the  predominating  minerals  of  the  tertiary  ? 


TERTIARY  ROCKS.  129 

of  the  buildings  of  Paris  are  built  of  the  three  first 
of  these  rocks,  which  are  largely  quarried  under  the 
city. 

Tertiary  rocks  were,  until  within  a  few  years, 
confounded  with  alluvial  and  diluvial  deposits,  and 
were  but  little  noticed.  It  is  now  ascertained,  that 
the  tertiary  formations  are  widely  spread  over  our 
islands  and  continents,  and  that  some  of  them  are 
of  considerable  thickness. 

The  mode  of  formation  of  the  tertiary  deposits  is 
almost  entirely  mechanical,  and  often  the  sediment 
was  coarse.  There  are  some  rocks  in  these  deposits 
formed  by  means  of  solution,  as  travertine,  gypsum, 
buhrstone,  and  some  other  siliceous  rocks. 

The  organic  remains  which  these  deposits  con- 
tain, and  particularly  the  absence  hitherto  without 
exception,  of  many  genera,  and  a  great  number  of 
species  of  animals,  characterize  particularly  this 
geological  epoch. 

The  stratification  of  the  tertiary  formations  is 
generally  distinct,  the  layers  being  parallel,  and  in 
most  instances  nearly  horizontal.  It  forms  hills  of 
moderate  elevation,  and  plains.  The  hills  are  round- 
ed and  with  slight  declivities,  except  on  the  coast, 
or  streams,  where  they  are  worn  away,  and  then  they 
sometimes  present  escarpments,  displaying  a  fiife 
section  of  the  strata. 


With  what  were  they  formerly  confounded  ?  What  rocks 
in  these  deposits  are  formed  by  means  of  solution  ?  What 
characterizes  this  geological  epoch  ?  How  is  the  stratifica- 
tion of  the  tertiary  generally  found  ? 


130  TERTIARY  ROCKS. 

"  The  most  remarkable  discovery  that  has  been 
made  respecting  the  tertiary  deposits,  is,  that  many 
of  them  contain  the  bones  of  mammiferous  quadru- 
peds, as  perfect  in  their  organization,  as  any  of  the 
existing  species  of  land  animals  ;  but  most  of  them 
belong  to  genera  or  species  that  are  extinct.  The 
tertiary  strata  are  further  remarkable,  for  presenting 
the  frequent  alternation  of  beds  containing  the  re- 
mains of  marine  animals,  with  other  beds,  that  con- 
tain  the  bones  of  land  animals,  or  fresh  water  shells. 
It  appears  that  the  tertiary  strata  were  chiefly  form- 
ed  in  detached  inland  seas,  or  lakes :  hence,  there 
is  a  considerable  diversity  in  the  thickness,  number, 
and  quality,  of  the  beds,  in  different  districts  or 
countries." 

It  may  be  well  here  to  remark,  that  the  remains 
of  mammiferous  animals,  or  those  that  suckle  their 
young,  are  not  found  below  the  tertiary  deposits.* 

The  principal  mammalia  belong  to  the  pachy- 
dermata,  carnivora,  and  cetacea.  Birds  are  not 
very  rare.  Reptiles  of  all  the  orders  occur,  but  tur- 
tles are  most  abundant.  Fishes  are  abundant  in 
some  localities.  Crustacea,  and  some  insects  occur. 

The  testaceous  molusca  are  very  abundant,  and 


What  remarkable  discovery  has  been  made  respecting  the 
tertiary  deposits  ?  What  is  remarkable  in  the  fossils  of  the 
alternating  beds  ?  Where  do  these  strata  seem  to  have  been 
formed  ?  Are  the  remains  of  mammiferous  animals  found 
below  the  tertiary  strata  ? 

*  There  are  a  few  exceptions  to  this  rule,  but  they  are  in  what  have 
been  termed  anomalous  deposits,  and  are  by  some  thought  to  be  only 
apparent,  but  not  real  exceptions. 


TERTIARY  ROCKS.  131 

those  most  numerous  are  what  are  called  littoral 
shells.  More  than  1200  species  have  been  deter- 
mined. The  most  characteristic  are  the  cerite, 
fusus,  cytherea  area,  and  nummulite.  The  trilobite, 
productus,  spirifer,  orthoceratite,  inoceramus,  catil- 
lus,  ammonite,  and  belemnite  are  never  found  in  the 
tertiary  in  such  a  state  as  to  indicate  their  having 
lived  there. 

The  vegetable  characters  are  no  less  important 
than  the  preceding. 

The  phyllites,  or  leaves  of  the  dicotyledons,  the 
stems  of  palms,  the  fruits  of  the  different  genera  of 
this  family,  are  common ;  and  many  of  them  are 
peculiar  to  these  formations.  The  true  fern  is  ex- 
ceedingly rare  in  the  tertiary,  and  no  stem  of  the 
calamite,  licopodites,  or  cycadies,  has  ever  been 
found  in  it.  [Brongniart,  Ter  de  Vceonce  du  Gl. 
p.  128.] 

"  During  the  deposition  and  consolidation  of  the 
upper  secondary  strata,  the  crust  of  the  globe  ap- 
pears to  have  remained  in  a  quiescent  state,  and  to 
have  experienced  few  violent  concussions  and  de- 
rangements, from  internal  causes." 

We  find  the  upper  secondary  and  tertiary  strata 
arranged  horizontally,  or  nearly  so,  over  the  inclin- 
ed lower  secondary,  transition,  and  primitive  rocks.* 


How  many  species  have  been  determined  as  existing  in 
the  tertiary  ?  Which  are  the  most  characteristic  ?  What 
are  the  vegetable  remains  ?  Do  the  upper  secondary  rocks 
seem  to  have  been  deranged  in  their  positions  during  their  de. 
position  ?  Are  the  upper  secondary  and  tertiary  strata  ar 
ranged  conformably  over  the  lower  rocks  ? 


132  TERTIARY  ROCKS. 

The  faults  and  dykes,  so  common  in  the  lower  stra- 
ta, and  in  the  vicinity  of  which  the  rocks  are  so 
much  bent,  contorted,  and  deranged  in  position, 
rarely  extend  into  the  upper  secondary  and  tertiary 
strata.  Where  these  latter  rocks  "  have  experienc- 
ed any  considerable  disturbing  force,  it  appears  to 
have  operated  at  a  comparatively  recent  period, 
after  the  deposition  of  the  tertiary  strata,"  for  they 
appear  to  have  been  raised,  or  depressed  together. 
The  cities  of  London  and  Paris  are  both  situated 
on  a  tertiary  deposit,  which  rests  upon  chalk,  and 
from  the  basin-shape,  they  are  termed  the  London 
and  Paris  chalk  basins. 

"  The  country  in  which  the  capital  of  France  is 
situated,  is  perhaps  the  most  remarkable  that  has  yet 
been  observed,  both  from  the  succession  of  different 
soils  of  which  it  is  formed,  and  from  the  extraordi- 
nary organic  remains  which  it  contains.  Millions 
of  marine  shells,  which  alternate  regularly  with  fresh 
water  shells,  compose  the  principle  mass.  Bones  of 
land  animals,  of  which  the  genera  are  entirely  un- 
known, are  found  in  certain  parts ;  other  bones,  re- 
markable for  their  vast  size,  and  of  which  some  of 
similar  genera  exist  only  in  distant  countries,  are 
found  scattered  in  the  upper  beds.  A  marked  char- 


Do  faults  and  dykes  often  extend  into  the  upper  secondary 
and  tertiary  strata  ?  Where  the  upper  secondary  and  ter- 
tiary rocks  have  been  deranged  in  their  position,  at  what 
period  does  this  arrangement  appear  to  have  taken  place  ? 
On  what  formation  do  the  cities  of  London  and  Paris  stand  ? 
On  what  do  the  tertiary  deposits  rest  ?  For  what  is  the  coun. 
try  around  Paris  most  remarkable  ?  What  show  evidences 
of  an  irruption  of  water  ? 


TERTIARY  ROCKS.  133 

acter  of  a  great  irruption  from  the  south  east,  is 
impressed  on  the  summits,  and  in  the  direction  of 
the  hills.  In  one  word,  no  country  can  afford  more 
instruction,  respecting  the  last  revolutions  which 
have  terminated  the  formation  of  the  present  con- 
tinents." 

The  fossil  shells  found  in  the  tertiary  strata,  most- 
ly belong  to  genera  now  existing  in  our  seas  ; 
yet  slight  variations  of  form,  have  induced  natural- 
ists to  regard  them  as  distinct  from  the  living  spe- 
cies. 

The  water  from  the  tertiary  strata  is  not  general- 
ly pure,  but  often  impregnated  with  various  salts : 
but  good  water  may  be  generally  obtained  by  boring 
through  these  deposits,  so  as  to  allow  the  water  to 
rise  from  the  lower 
strata.  The  tertiary 
strata  being  situated  in 
basin  shaped  hollows, 
thus,  pools,  ponds,  or 
streams  of  water,  situated  at  a,  would  let  the  water 
penetrate  between  the  strata,  so  that  if  they  be  bor- 
ed at  &,  the  water  would  rise  to  a  level  with  that  at 
a.  If  b  should  lie  below  the  level  of  a,  the  water 
would  spout  up,  or  at  least,  run  over,  at  the  surface 
of  the  earth  at  b.  Good  water  is  in  this  way  often 
obtained  from  a  depth  of  several  hundred  feet,  and 
not  only  from  boring  through  the  tertiary  rocks,  but 

Do  any  of  the  fossil  shells  of  the  tertiary  strata  belong  to 
genera  now  existing  ?  Is  the  water  obtained  from  the  ter- 
tiary strata  pure?  With  what  is  it  often  impregnated? 
How  may  good  water  be  obtained  ?  May  water  be  obtained 
from  great  depths  by  this  means  ? 

12  ' 


134  TERTIARY  ROCKS. 

in  any  of  the  classes  of  rocks.  It  however  requires 
much  judgment  to  determine  whether  water  may  be 
obtained  in  this  way,  in  any  particular  locality. 

The  tertiary  strata  of  the  Paris  chalk  basin,  show 
not  only  the  remains  of  sea  animals  and  land  quad- 
rupeds, but  also  those  of  birds,  among  which  may 
be  mentioned  the  duck,  pelican,  curlew,  woodcock, 
starling,  and  sea-lark.  Feathers  have  in  some  in- 
stances been  found,  shewing  distinctly  their  impres- 
sions, in  the  gypsum.  Fish  are  not  unfrequently 
found  imbedded  in  these  strata,  but  they  are  more 
common  in  bituminous  marls,  and  slates  of  the  up- 
per secondary  series. 

Fossil  fish  are  found  very  abundantly  in  the  slaty 
marl  quarries  of  Monte  Bolca,  near  Verona ;  105 
species  according  to  Brocchi,  or  90  according  to 
Blainville  have  been  found  in  those  quarries;  and 
many  of  them  are  different  from  any  species  known 
to  exist  in  the  neighbouring  seas,  or  even  in  any 
part  of  the  earth.  The  forms  of  the  fishes  are  well 
preserved,  and  particularly  the  bony  parts.  The 
animal  matter  is  indurated,  mixed  with  earthy  mat- 
ter, and  is  of  a  brown  colour,  and  is  so  thick  as  to 
project  from  the  stone  and  admit  of  being  separated 
from  it.  The  animal  matter  is  brittle,  and  breaks 
with  a  glossy  fracture,  and  bears  some  resemblance 
to  glue.  The  bones  are  sometimes  converted  to 
calcareous  spar. 

Are  the  remains  of  birds  ever  found  imbedded  in  rocks  ? 

Are  fish  found  fossil  ?     Are  they  most  common  in  the  upper 

f  secondary,  or  tertiary  strata  ?     Where  have  they  been  found 

abundantly  ?     How  many  species  have  been  found  there  1 

What  peculiarities  distinguish  the  animal  matter  ? 


DILUVIAL  DEPOSITS.  135 

Fossil  fish  have  been  found  in  a  bituminous  shale, 
near  Middletown,  Conn,  and  in  Sunderland,  Mass., 
in  considerable  numbers.  Fishes  appear  to  have 
been  suddenly  and  forcibly  enveloped  in  the  sub- 
stance containing  them,  if  we  may  judge  from  the 
contorted  posture  into  which  they  had  thrown  them- 
selves, apparently  with  a  view  to  escape  the  terrible 
catastrophe  of  which  they  are  monuments. 


CHAPTER  X. 
DILUVIAL  DEPOSITS. 

The  crumbling  of  rocks  is  constantly  going  on 
from  the  effects  of  the  weather  :  all  bare  and  lofty 
cliffs  and  mountains  are  gradually  wearing  down, 
and  the  process  continues,  "  until  they  are  covered 
with  soil  and  vegetation,  which  protect  them  from 
further  decay." 

"Besides  the  causes  which  at  present  operate 
to  reduce  the  most  exposed  and  prominent  parts  of 
the  earth's  surface,  and  transport  their  materiafs 
into  plains,  or  to  the  sea-shore,  there  are  evident  in- 
dications of  the  destructive  effects  of  ancient  inun- 


Have  they  been  found  in  the  United  States?  Do  they 
seem  to  have  been  destroyed  suddenly  ?  Is  there  any  thing 
to  indicate  that  a  deluge  has  swept  over  the  land  ?  What 
are  evidences  of  this  ? 


136  DILUVIAL  DEPOSITS. 

nations,  which  have  swept  over  the  surface  of  the 
present  continents,  excavated  new  valleys,  torn  off  the 
summits  of  the  loftiest  mountains,  and  spread  their 
ruins  in  immense  fragments  over  distant  regions. 

"  The  sand,  soil,  or  fragments,  brought  down  hy 
rivers  and  spread  along  their  hanks,  or  at  their 
mouths,  are  called  alluvial  depositions.  The  blocks 
of  rock,  and  the  beds  of  gravel  spread  or  scattered 
on  the  surface  of  the  ground,  composed  of  stone,  or 
fragments  foreign  to  the  district  in  which  they  are 
spread,  and  which  frequently  cover  the  bones  of 
unknown  species  of  quadrupeds,  are  called  diluvial 
depositions,  viz  :  depositions  which  have  been  form- 
ed by  a  deluge." — [BakeweWs  Geology.'] 

The  diluvial  deposits  are  either  superficial,  or 
buried  only  under  alluvion. 

The  materials  are  usually  coarse,  and  composed 
of  gravel,  pebbles,  and  blocks,  of  a  great  variety  of 
rocks  aggregated  without  any  regularity. 

These  materials  are  sometimes  cemented  together 
by  carbonate  of  lime,  or  other  mineral,  that  had 
been  in  solution,  and  afterwards  was  deposited  in 
their  interstices.  Some  of  these  rocks  are  conglom- 
erates, pudding  stone,  and  osseous  breccias.  The 
travertins  of  this  age  have  been  formed  entirely  from 
solution. 

.Gravel  and  pebble  beds  contain  the  remains  of 
extinct  quadrupeds,  but  few  remains  of  man,  or  his 


t 

What  are  alluvial  depositions?  What  are  diluvial  de- 
posits ?  What  arc  the  materials  of  the  diluvial  composed  of? 

How  are  they  sometimes  cemented  together  ?  What  are 
some  of  these  rocks  ?  What  of  gravel  and  pebble  beds  ? 


DILUVIAL  DEPOSITS.  137 

arts.  They  are  in  situations  where  no  powerful 
currents  can  reach  from  actual  existing  causes. 
Some  of  the  tertiary  conglomerates  might  be  con- 
founded with  the  diluvial  deposits. 

The  bones  and  skeletons  of  large  animals  and 
especially  the  mammoth,  are  found  in  diluvial  gravel 
in  many  countries.  In  Siberia  the  tusks  of  the  fos- 
sil elephant,  are  found  in  the  diluvial  banks  of  al- 
most every  river,  and  the  ivory  from  these  skeletons 
is  an  article  of  export. 

"  It  is  said  that  the  skeleton  of  a  whale  lies  on  the 
top  of  the  mountain  Sandhorn,  on  the  coast  of  the 
northern  sea.  The  mountain  is  3000  feet  high,  and 
there  is  no  cause  that  could  have  conveyed  the  whale 
to  that  elevation  except  a  deluge  rising  to  that 
height." 

In  1824  the  remains  of  a  whale  were  found  on 
the  westernmost  Staffen,  a  mountain  in  Finmark, 
at  an  elevation  of  800  feet  above  the  ocean."  [Sil- 
limarfs  Consistency  of  Geol.  with  Sacred  History, 
in  BakeweWs  Geol.  2d.  Am.  Ed.  p.  411.] 

The  phenomena  of  the  diluvial  ruins  are  highly 
important,  inasmuch  as  they  demonstrate  the  nature 
of  the  causes  that  have  modified  the  present  surface 
of  our  planet,  and  by  the  quantity  of  these  wrecks* 
we  can  form  an  estimate  of  the  forces  in  action  to 
produce  them. 


What  animal  remains  are  found  in  diluvial  gravel?  On 
what  mountain  is  the  skeleton  of  a  whale  said  to  be  ?  And 
how  is  it  accounted  for  ?  Where  has  the  remains  of  a  whale 
been  found  in  1824  ?  how  high  is  this  mountain  ?  What  do 
the  diluvial  ruins  demonstrate  ? 

12* 


138  DILUVIAL  DEPOSITS. 

The  phenomena  of  erratic  blocks  are  some  of 
the  most  striking,  general,  and  inexplicable  in  geol- 
ogy. Some  of  the  erratic  blocks  contain  1500  cu- 
bic metres, —to  4000  tons  weight.  [Vido  Brong- 
niart,  Tab.  des  Terr  airs,  p.  84.] 

Ohio,  in  which  the  rocks  are  secondary  lime- 
stones, sandstones,  &c.,  is  found  to  have  boulders* 
of  various  primitive  rocks,  as  granite,  sienite,  &c., 
scattered  abundantly  over  some  parts  of  its  surface, 
and  no  rocks  of  these  kinds,  are  known  to  be  nearer 
than  on  the  north  side  of  the  great  lakes. 

The  Alps,  and  many  parts  of  Germany,  Russia, 
&c.  have  their  surfaces  strewed  with  huge  blocks 
and  rounded  masses  of  primitive  rocks,  which  are 
said  to  have  been  evidently  brought  from  Denmark, 
Sweden  and  Norway,  for  there,  exactly  the  same 
rocks,  containing  the  same  minerals,  and  present- 
ing the  same  appearances,  occur. 

Similar  appearances  occur  in  every  country. 
Sand,  gravel,  and  pebbles,  are  of  still  more  frequent 
occurrence,  which  appear  to  have  been  transported 
from  their  original  situations,  and  deposited  in  new 
ones.  Most  of  these  materials  have  their  angles 
rounded  off,  and  appear  to  have  been  rubbed  and 
worn  by  friction  against  each  other,  like  the  pebbles 
in  a  river,  or  on  the  sea-shore. 


What  is  said  of  erratic  blocks  ?     What  are  boulders  ? 

*  Boulders  are  the  loose,  rounded  masses  of  rock  that  we  see  scat- 
tered over  and  in  the  soil,  in  various  parts  of  the  country.  Rocks  are 
said  to  be  in  place,  when  they  are  in  native  ledges,  or  strata.  Boui- 
ders  are  rocky  masses,  not  in  place. 


DILUVIAL  DEPOSITS.  139 

One  remarkable  circumstance  in  relation  to  these 
traveled  fragments  is,  that  we  often  find  them  of 
great  magnitude,  and  separated  from  their  parent 
bed,  by  the  intervention  of  deep  valleys  and  seas ; 
and  it  seems  impossible,  that  the  force  of  currents, 
however  impetuous,  can  have  driven  them  up  the 
steep  sides  of  mountains,  or  through  the  deep  beds 
of  seas. 

The  explanation  that  seems  more  reasonable,  is, 
that  they  were  transported  on  ice  bergs,  before  the 
continents  were  uncovered  by  the  waters  of  the 
deluge,  and  deposited  where  they  are  now  found,  by 
the  gradual  melting  of  the  ice  after  it  had  grounded, 
or  even  when  floating*  Scoresby  counted  500  ice 
bergs  in  North  latitude  69°  and  70°,  and  many  of 
them  were  loaded  with  beds  of  rock,  earth  and  grav- 
el, of  great  thickness.  Such  islands  of  ice  have 
been  known  to  drift  to  the  Azores,  from  the  North, 
and  to  the  Cape  of  Good  Hope,  from  the  South. — 
[Phil.  Magazine.'] 

Other  explanations  that  have  been  offered  and  are 
most  plausible,  are : 

1st.  Deluc's,  who  suggested  that  these  blocks  had 
been  thrown  into  the  air  by  the  same  power  that  had 
elevated  the  mountains,  and  had  fallen  at  different 
distances  according  to  the  force  and  angle  of  pro- 
jection. 

2d.  De  Buch's,  who  supposes  that  they  were  in 


What  is  remarkable  in  the  situation  of  these  rocks  ?  What 
explanation  is  offered  of  their  transportation  ?  Do  ice  bergs 
now  often  transport  large  masses  of  rock  far  from  their  origi- 
nal situation  ?  What  is  Deluc's  explanation  ?  What  is  De 
Buch's  supposition  ? 


140  DILUVIAL  DEPOSITS. 

their  present  place  before  the  last  great  convulsion 
of  the  earth's  surface,  and  when  on  high  mountains, 
that  the  mountains  have  been  elevated  since  that 
period. 

It  is  believed  that  these  theories  have  been  aban- 
doned by  all,  and  there  are  numerous  facts  which 
militate  against  all  the  theories  that  have  been  pro- 
posed, except  that  of  transport  by  floating  ice. 

There  is  no  difficulty  in  supposing  the  transport 
of  gravel,  sand,  or  pebbles,  by  the  action  of  run- 
ning water,  to  the  situations  in  which  they  are  found, 
when  we  take  into  view  the  violence  of  the  cur- 
rents which  must  have  been  produced  during  the 
rise  and  fall  of  the  waters  of  the  deluge. 

"  In  order  to  appreciate  justly  the  effect  of  such 
a  tremendous  rush  of  waters,  we  must  compare 
it  not  only  with  common  tides,  but  with  those  more 
violent  ones  with  which  we  are  acquainted."  "Be- 
tween the  Mata  Cape  and  the  North  Cape,  in  the 
place  where  the  great  canal  of  the  river  Amazon  is 
most  confined  by  the  islands,  the  tide  presents  a, 
singular  phenomena.  During  the  three  days  near- 
est the  full  and  new  moons,  (the  times  of  the  high 
tides,)  the  sea,  instead  of  employing  six  hours  to 
rise,  attains  its  highest  elevation  in  the  space  of  one 
or  two  minutes.  It  may  be  supposed  that  this  is  not 
effected  very  quietly  :  a  terrific  noise  is  heard  at  the 
distance  of  one  or  two  leagues,  which  announces 
the  pororoca,  or  bore,  (such  is  the  name  the  Indians 


Is  there  any  difficulty  in  accounting  for  the  transport  of 
gravel,  sand  and  pebbles  ?  What  is  said  of  the  pororoca  of 
the  Amazon  ? 


DILUVIAL  DEPOSITS.  141 

of  the  district  give  to  this  terrible  tide.)  As  it  ad- 
vances, the  noise  increases,  and  presently  one  be- 
holds a  promontory  of  water,  from  12  to  15  feet  in 
height ;  then  a  second,  then  a  third,  and  often  a 
fourth,  which  follow  close  on  each  other,  and  which 
occupy  the  whole  breadth  of  the  canal.  This  surge 
advances  with  prodigious  rapidity,  breaking  down 
and  shaving  clean  away,  every  thing  that  opposes 
it.  Wherever  it  passes,  the  coast  is  laid  as  smooth 
as  if  it  had  been  intentionally  and  carefully  swept. 
— [Sillimari's  Outline,  in  BakeweWs  Geology.'] 

At  the  mouth  of  a  river  in  Nova  Scotia,  a 
schooner  of  32  tons,  laden  with  live  stock,  was 
lying  with  her  side  to  the  tide,  at  the  influx  of  the 
bore,  which  was  then  about  10  feet  in  perpendicu- 
lar height.  No  sooner  had  this  mass  of  water 
reached  the  vessel,  than  that  great  body  was  turned 
over  like  a  barrel,  and  presently  disappeared.  Af- 
ter the  tide  had  ebbed,  the  schooner  was  so  totally 
absorbed  in  the  sand,  that  the  upper  rail  of  the  deck 
was  alone  visible." 

"  The  tides  in  the  Bay  of  Fundy  are  said  to  rise 
sixty  feet, — to  come  roaring  in  like  a  mighty  rushing 
flood, — and  that  people  and  animals  upon  the  beach, 
sometimes  with  difficulty  escape  writh  their  lives."  * 

"On  the  14th  Oct.  1822,  a  wave,  which,  during 
a  storm,  broke  against  the  pier  of  Ramsgate,  and 
was  dashed  upwards  to  a  height  of  about  14  feet, 
fell  again  upon  the  stone  pavement  of  the  pier  head  ; 
and,  by  the  force  of  its  reaction,  raised  a  361b.  car- 
ronade,  with  its  carriage,  over  a  stone  ledge,  and 


What  is  said  of  the  effects  of  the  tide  in  the  Bay  of  Fundy  ? 


142  DILUVIAL  DEPOSITS. 

precipitated  it  into  the  sea."  The  efforts  of  20 
men  would  have  been  required  to  produce  the  same 
effect. 

"In  the  great  tempest  of  Sept.  1815,  among  ma- 
ny similar  effects,  which  happened  all  along  the 
shores  of  New  England,  a  vast  ridgy  wave,  raised 
by  the  hurricane,  came  suddenly,  in  an  overwhelm- 
ing deluge,  upon  the  lower  town  of  Providence,  in 
Rhode  Island,  and  by  its  force,  entire  rows  of  houses, 
and  stores,  and  warehouses,  were,  in  a  few  minutes, 
prostrated.  Ships  of  300  and  400  tons,  were  thrown 
upon  the  wharves,  knocking  down  large  buildings 
by  their  momentum  :  some  were  carried  into  the 
town,  thrusting  their  jib  booms  in  at  the  2d  and  3d 
stories  of  houses  ;  others  were  lodged  in  the  streets  ; 
and  a  number,  and  those  some  of  the  largest  class, 
(among  them  the  Ganges,  formerly  a  sloop  of  war,) 
after  carrying  away  a  strong  bridge,  were  driven 
through  a  bay,  usually  too  shallow,  even  for  small 
craft,  and  were  thrown  up  high  and  dry,  upon  a 
beach,  where  the  salt  water  has  never  come  again." 
— [Silliman's  Outline  in  BakeweWs  Geology.] 

The  effects  of  torrents,  and  of  lakes  bursting  their 
boundaries,  are  still  more  striking,  and  I  beg  leave 
to  refer  the  reader  to  the  American  Journal  of  Sci- 
ence, vol.  iv,  p.  125,  and  xv,  art.  ii.  xi,  p.  39,  for 
accounts  of  such  phenomena,  which  have  occurred 
within  a  few  years,  and  in  our  own  country. 

The  evidences  of  the  deluge  are  imprinted  in  an 
imperishable  manner,  on  all  parts  of  the  earth,  in 


What  were  the  effects  of  the  wave  that  rushed  into  the 
town  of  Providence  during  the  storm  of  1815  ? 


DILUVIAL  DEPOSITS.  143 

the  transported  materials,  which  have  been  spoken 
of,  and  in  the  valleys  scooped  out  of  the  originally 
continuous  strata,  of  which  mention  has  been  made 
in  the  chapter  on  stratification.  Supposing  the 
highest  elevation  of  the  waters  to  have  been  51-2 
miles  :  as  they  were  40  days  in  rising,  they  rose  at 
the  rate  of  181  feet  in  the  time  of  a  common  flood, 
or  ebb  tide. 

If  we  now  glance  at  the  effects  of  the  tides  which 
have  been  mentioned  in  the  Amazon  ;  on  the  coast 
of  Nova  Scotia;  of  the  storm  of  1815,  in  New 
England  ;  that  on  the  Catskills,  in  1819  ;  and  that 
on  the  White  Mountains,  in  1826,  how  much  more 
powerful  must  have  been  the  effects,  where  the  water 
was  rising  continually,  and  acquiring  additional 
force  and  velocity,  during  its  40  days  rise  of  the 
deluge. 

"  It  is  not  easy  to  exalt  the  imagination  to  the 
adequate  conception  of  the  terrors  of  that  awful 
catastrophe.  The  inconceivably  violent  torrents 
and  cateracts,  every  where  descending  from  the 
hills  and  mountains,  and  meeting  a  tide,  rising  at 
the  rate  of  more  than  700  feet  in  a  day,  must  have 
been  resisted  and  aggavated  in  force,  wherever  it 
encountered  the  land,  and  still  more  by  the  hills  a«4 
the  mountain  ridges.  Impelled  with  resistless  vio 
lence — it  must  have  swept  over  the  surface,  with  a 
force  vastly  greater  than  any  thing  we  now  know, 
of  the  mightiest  rushing  waters.  It  evidently  roll- 


Do  valleys  appear  to  have  been  scooped  out  by  the  deluge  t 
Must  the  waters  of  the  deluge  have  risen  more  rapidly  than 
our  highest  tides  ? 


144  DILUVIAL  DEPOSITS. 

ed  every  where  over  the  various  inequalities  of  the 
land  in  tremendous  agitated  billows ;  and  where  it 
was  narrowed  by  ridges,  and  hills,  and  mountains, 
and  thus  forced  through  valleys  and  defiles,  it  must 
have  presented  innumerable  raging  torrents  and  ca- 
taracts, of  awful  height,  force  and  magnitude,  com- 
pared  with  which,  even  Niagara  would  be  insignifi- 
cant. " — [Sillimaii's  Outline.  ] 

The  diluvial  deposits  in  some  parts  of  the  earth, 
are  rich  in  metals,  ores,  and  gems. 

Deposits  containing  these  substances  are  gene- 
rally loose,  or  but  slightly  aggregated,  composed  of 
sand,  gravel,  pebbles  and  boulders,  more  or  less 
rounded  by  attrition. 

The  materials  composing  these  rich  deposits,  is 
mostly  a  siliceous  sand  or  gravel,  which  is  often 
highly  ferruginous.  The  beds  are  in  many  in- 
stances  of  considerable  thickness,  filling  broad  val- 
leys ;  covering  elevated  plains  and  hills  of  moderate 
declivity. 

The  minerals  generally  found  in  these  deposits, 
are  hyaline  quartz,  amethysts,  jasper,  and  titanife- 
rous  iron  sand. 

Of  gems  there  are  crystals  with  worn  edges,  as 
sapphire,  ruby,  spinelles,  crysoberyl,  topaz,  zircons, 
and  diamond. 

Diamonds  have  been  found  only  in  Brazil,  Borneo, 
India,  and  Russia. 


In  what  are  the  diluvial  deposits  rich  ?  What  is  the  ma- 
terial composing  them  ?  What  of  the  beds  in  which  they 
are  found  ?  What  kinds  of  minerals  are  generally  found  in 
these  deposits  ?  What  kinds  of  gems  ? 


DILUVIAL  DEPOSITS.  145 

Of  the  metals ;  gold,  platinum,  several  metals  as- 
sociated with  platinum,  red  oxide  of  titanium,  mag. 
netic  iron  sand,  micaceous  and  specular  iron  ore, 
and  the  oxide  of  tin  are  the  most  important. 

Gold  is  found  most  abundantly  in  the  washings 
in  Russia  in  Asia,  in  Brazil,  South  America,  and  in 
the  southern  and  middle  States  of  the  United  States. 

Platinum  is  found  in  South  America,  and  in  Asia 
at  the  foot  of  the  Oural  mountains. 

Gold  is  always  found  in  connection  with  platinum, 
but  the  reverse  is  not  always  true. 

Oxide  of  tin  occurs  in  granitic  gravel,  which  is 
generally  in  the  vicinity  of  the  rocks  from  which  it 
was  derived. 

Caves  have  been  found  in  England,  France,  and 
Germany,  containing  immense  numbers  of  the  bones 
of  animals,  which,  in  some,  are  imbedded  under  a 
kind  of  yellowish  earth,  like  that  which  is  supposed 
to  have  been  deposited  while  the  waters  were  rest- 
ing upon  the  earth,  during  the  deluge. 

Some  of  these  caves  appear  to  have  been  the  dens 
of  antediluvial  carnivorous  animals,  and  into  others 
it  appears  that  the  animals  may  have  retired  to  es- 
cape the  deluge ;  or  may  have  fallen  in,  or  been 
washed  in  through  fissures  communicating  with  the 
surface  of  the  earth. 

The  bones  of  some  of  the  animals  show  the  marks 


What  kinds  of  metals  ?  In  what  countries  are  they  mostly 
found  ?  Are  the  bones  of  animals  found  in  great  numbers  in 
the  caves  of  England,  Germany  and  France  ?  Are  these  in 
the  loose  earth  of  recent  deposit,  or  in  diluvial  mud  ?  What  do 
some  of  th  jse  caves  appear  to  have  been  ?  What  do  some  of 
the  bones  show  ? 

13 


146  DILUVIAL  DEPOSITS. 

of  teeth,  as  though  they  had  been  gnawed  ;  and  the 
bones  of  the  hyena,  bear,  wolf,  fox,  dog,  horse,  ox, 
and  a  great  variety  of  animals  are  found  in  them. 
The  earth,  in  which  these  bones  are  imbedded,  is 
generally  covered  by  a  stony  mass,  since  formed. 
In  some  of  the  caves,  all  the  earth  appears  to  have 
been  formed  by  animal  decomposition. 

Bone  breccias,  fissures,  and  caverns.  These  are 
generally  classed  with  diluvial  deposits,  although  it 
is  probable  many  of  them  are  more  recent. 

The  fissures  and  caves  containing  the  bones,  and 
bone  breccias,  are  in  limestone ;  and  the  Jura  lime- 
stone is  the  rock  in  which  they  are  most  abundant. 

The  fissures  are  filled  with  fragments  of  rock, 
some  rounded,  some  angular,  and  cemented  together 
by  finer  materials  of  the  same  kind,  and  calcareous 
matter  deposited  in  the  interstices  from  solution  in 
water.  The  colour  is  variable ;  but  red  is  most 
common  from  carbonate  and  oxide  of  iron.  The 
bones  are  those  of  vertebrated  animals  and  mostly 
of  mammalia ;  some  are  rounded  and  worn,  some 
broken,  and  others  are  perfect,  and  imbedded  in  the 
breccia. 


Is  the  earth  in  which  these  bones  are  imbedded,  ever  cov- 
ered by  a  stony  mass  ?  In  some  of  the  caves,  does  all  the 
earth  appear  to  have  been  formed  of  animal  matter  ?  What 
are  generally  classed  with  diluvial  deposits  ?  What  is  pro- 
bable respecting  them  ?  In  what  rock  are  they  most  abun- 
dant ?  With  what  are  the  fissures  filled  ?  How  are  these 
fragments  cemented  together  ?  What  colour  do  they  pre- 
sent ?  What  species  of  bones  are  these  ?  How  do  they  ap 
pear? 


DILUVIAL  DEPOSITS.  147 

Land  and  fresh  water  shells  are  not  uncommon 
in  these  breccias  ;  and  bones  of  birds  are  sometimes 
also  found.  The  fissures  always  communicate  with 
the  surface  of  the  earth ;  or  at  least,  none  have  been 
cited  as  closed  in  every  direction  by  solid  beds  of 
rock,  without  having  been  since  found  to  have 
evidently  communicated. 

Of  the  organic  remains  of  the  breccias  of  the  fis- 
sures, the  palaeotherium,  chaeropotamus,  deer,  ante- 
lope,  cat,  two  species  of  bear,  and  the  rabbit  are 
among  the  most  common.  The  fissures  in  which 
they  are  contained  have  their  angles  rounded,  and 
the  concave  cavities  in  the  sides,  show  as  if  they  had 
once  been  the  passages  through  which  currents  of 
water  had  flowed.  This  would  account  for  some  of 
the  fragments  and  bones  being  rounded  in  their 
forms.  Many  of  the  animals  probably  fell  into  or 
were  lost  in  the  fissures,  and  unable  to  escape. 

Bone  caves  are  subterranean  sinuous  caverns,  pre- 
senting in  different  parts  of  their  course,  expansions 
and  contractions  in  breadth  and  height.  The  sides 
are  not  parallel,  but  appear  as  if  worn  and  corroded 
by  the  action  of  water,  or  other  solvent  material. 
They  are  of  various  degrees  of  declivity  from  the 
surface,  some  penetrating  horizontally  from  the  base 
or  sides  of  hills,  others  at  some  intermediate  angle/ 
or  vertically. 


Are  shells  and  bones  of  birds  sometimes  found  ?  With  what 
do  th  e  fissures  communicate  ?  What  are  the  most  common 
of  the  organic  remains  of  the  breccias  of  the  fissures  ?  What 
do  the  fissures  in  which  they  are  contained  show  ?  What 
would  this  account  for  ?  What  are  bone  caves  ?  How  are 
the  sides  formed  ? 


148  DILUVIAL  DEPOSITS. 

These  caverns  generally  show  the  naked  lime- 
stone in  which  they  are  contained  ;  and  they  are 
more  or  less  filled  with  two  kinds  of  rock  of  different 
composition  and  origin.  These  are, 

1st.  Earthy  materials  sometimes  entirely  loose, 
mingled  with  fragments  of  rock  and  bones,  occu- 
pying the  inferior  parts  of  the  cavern. 

2cl.  Crystalline  calcareous  concretions,  called  sta- 
lactites, and  stalagmites,  which  cover  the  roof,  sides, 
and  floor,  entirely,  or  in  part,  and  often  form  a  thick 
crust  over  the  earth,  and  fragments  of  rock  and 
bones.  Often  the  materials  of  the  first  are  cement- 
ed together  by  the  calcareous  depositions  of  the  se- 
cond, in  a  breccia,  similar  to  the  bone  breccia  of 
the  fissures.  The  bones  are  scarcely  altered.  Of 
the  remains  found  in  caverns  three-fourths  belong  to 
bears,  one-sixth  to  the  hyena,  and  one- twelfth  to  the 
remaining  animals.  These  are  the  elephant,  rhino- 
ceros, horse,  ox,  hog,  camel,  sheep,  cat,  two  species 
of  weazel ;  pole  cat,  badger,  wolf,  rat,  hare,  and 
birds. 

Some  human  bones  have  been  found  in  caves  of 
this  description  in  France,  so  situated  as  to  induce 
the  idea  that  the  subjects  of  them  were  destroyed  by 
the  deluge.  Similar  relicts  have  been  discovered  in 
diluvial  gravel,  at  the  depth  of  about  50  feet ;  and 


What  do  these  caverns  show  ?  What  are  the  rocks  with 
which  these  caverns  are  filled  composed  of  ?  Are  they  often 
cemented  together  ?  What  are  the  proportions  of  the  remains 
of  the  different  animals?  Have  human  bones  been  found  in 
caves  ?  What  idea  does  their  situation  induce  ?  Have  human 
remains  heen  found  in  diluvial  gravel  ?  At  what  depth  ? 


ALLUVIAL  DEPOSITS.  149 

remains  of  this  kind  have  also  been  found  imbedded 
in  a  rock  of  recent  origin,  and  which  is  even  now 
in  the  process  of  formation,  enclosing  every  thing 
thrown  upon  it  by  the  surf. 

It  is  a  remarkable  fact,  that,  notwithstanding  the 
great  variety  of  fossils  observed  in  the  rocks,  the 
remains  of  man  are  not  found  fossil  until  we  come 
to  the  diluvial  deposits.  Geological  facts  show,  that 
the  various  plants  and  animals  were  created  in  the 
some  order  as  mentioned  in  the  Mosaic  account,  and 
that  man  was  created  last,  as  we  find  his  remains 
only  in  those  deposits  laid  down  since  all  those  great 
changes  and  convulsions,  which  destroyed  so  many 
millions  of  millions  of  animated  beings,  and  formed 
some  of  the  rocks  of  their  remains. 


CHAPTER  XI. 
ALLUVIAL  DEPOSITS. 

These  deposits  are  the  most  superficial  of  all  the 
formations ;  and  the  materials  forming  them  gene-* 
rally  indicate  that  they  were  deposited  from  water ; 
and  they  appear  in  most  cases,  to  have  separated 
from  tranquil  water  rather  than  from  violent  cur- 
rents. 


Have  the  remains  of  man  been  found  imbedded  in  rock  ? 
In  what  kind  of  rock  ?     In  what  deposits  only  do  we  find  the 
remains  of  the  human  race  ?     What  do  the  alluvial  deposits 
indicate  ?     How  do  they  appear  in  most  cases  ? 
13* 


150  ALLUVIAL  DEPOSITS. 

Alluvial  deposits  are  forming  every  day.  They 
envelope  the  remains  of  animals  that  still  exist  on 
the  surface  which  they  contribute  to  form ;  and  they 
are  also  mingled  in  many  places,  with  the  remains 
of  animals  which  have  lived  in  recent  times,  and 
have  disappeared,  either  by  the  effects  of  civilization 
or  other  local  causes. 

These  remains  are  hardly  altered ;  being  perhaps 
blackened  or  whitened,  according  to  the  influences 
to  which  they  may  have  been  subjected.  In  allu- 
vion we  find  the  remains  of  human  beings,  of  their  in- 
dustry and  arts.  The  stone  arrow  heads,  axes,  and 
other  cutting  instruments,  fragments  of  pottery,  re- 
mains of  furnaces,  and  the  metals  smelted  under  the 
surface  are  familiar  to  every  one.  The  alluvial  beds 
taken  as  masses,  are  all  of  loose  earth,  and  are  never 
covered  by  rocky  beds.  Tufa  is  sometimes  deposit, 
ed  from  calcareous  springs  over  more  ancient  allu- 
vion, but  the  beds  are  always  of  small  extent. 

It  is  often  difficult  to  distinguish  between  the  allu- 
vial and  diluvial  deposits,  but  the  distinction  is  in 
general  of  little  consequence.  All  those  causes 
which  are  at  present  in  action  to  produce  changes 
upon  the  surface  of  the  earth,  such  as  the  transport 
of  materials  by  torrents,  rains,  streams,  tides,  cur- 


Are  alluvial  deposits  often  formed  ?  What  do  they  en- 
velope? With  what  are  they  mingled  in  many  places? 
Are  the  remains  of  man  and  his  arts  abundant  in  this  forma, 
tion  ?  What  of  alluvial  beds  ?  Is  it  always  easy  to  distin- 
guish between  the  alluvial  and  diluvial  deposits  ?  What  are 
the  causes  of  alluvial  deposits? 


ALLUVIAL  DEPOSITS.  151 

rents  in  the  ocean,  winds,  springs,  and  the  labours  of 
animals,  as  shell  fish,  and  corals,  in  elevating  banks 
and  reefs  in  the  ocean ;  the  growth  and  decay  of 
plants,  as  in  peat-bogs,  and  swamps  ;  the  formation 
of  bog  iron  ore;  and  calcareous  depositions  from 
springs,  are  classed  as  alluvial ;  while  all  those  ma- 
terials which  have  been  transported  to  situations 
where  the  waters,  under  existing  causes,  cannot 
reach  them,  the  scooping  out  of  some  valleys,  and 
uncapping  of  some  mountains,  are  referred  to  dilu- 
vial agency.  Torrents  often  remove  masses  of 
rock,  of  many  tons  weight,  to  considerable  dis- 
tances ;  tear  up  trees,  and  bury  them  under  deep 
masses  of  rocks,  pebbles,  gravel  and  sand.  Rains 
wash  off  the  loose  materials  on  the  hills :  some  of 
this  is  carried  into  the  larger  streams ;  and  these, 
when  the  waters  are  high,  wear  away  the  banks  in 
some  places,  and  deposit  the  materials  in  others. 
Thus  there  is  a  constant  tendency  to  level  the 
country,  wear  down  its  inequalities,  and  deposit  the 
materials  in  the  sea.  The  making  of  land,  by  the 
deposit  of  materials  thus  brought  down  by  rivers, 
is  well  known,  and  illustrated  by  the  Mississippi, 
Ganges,  and  many  others.  The  mouths  of  the  Mis- 
sissippi  are  more  than  100  miles  from  its  original 
entrance  into  the  Gulf  of  Mexico,  and  for  many  hun- 
dreds of  miles  above,  all  the  land  seen  from  its  banks, 


How  do  you  distinguish  diluvial  from  alluvial  deposits  ? 
What  is  the  constant  tendency  of  rains  and  streams  ?  Do 
rivers  ever  deposit  their  materials  in  the  sea  ?  Are  the 
mouths  of  the  Mississippi  far  from  the  original  entrance  of 
the  river  to  the  Gulf  of  Mexico  ?  Are  the  other  alluvial 
deposits  of  the  Mississippi  extensive  ? 


152  A.LLUVIAL  DEPOSITS. 

with  the  exception  of  now  and  then  a  sand  or  clay 
bluff,  is  alluvial. 

M.  Lardy  has  described  a  fall  of  a  part  of  the 
Dent  du  midi,  one  of  the  high  Alps,  which  took  place 
on  the  26th.  Aug.  1835. 

On  the  25th.  there  was  a  violent  storm  all  around 
the  mountain,  which  was  often  struck  by  lightning. 
On  the  26th.  a  large  portion  of  the  peak  broke  off 
from  the  eastern  edge,  and  fell  with  a  dreadful  crash 
upon  the  glacier  on  the  southern  side  of  the  moun- 
tain, and  in  its  descent  drew  along  with  it  an  im- 
mense portion  of  this  glacier.  This  enormous  mass 
of  mixed  stone  and  ice  fell  into  a  deep  ravine,  through 
which  the  torrent  of  St.  Bartholemy  flows.  A  mass 
as  it  were  a  mountain  of  black  viscid  mire  speedily 
flowed  from  the  gorge  of  the  ravine,  and  bore  on  its 
surface  vast  blocks  and  masses  of  solid  rock.  This 
semi-liquid  mass,  crossed  the  valley  towards  the 
Rhone  like  a  flow  of  lava,  crushing  and  bearing 
away  a  forest  of  pines  in  its  course.  The  Rhone 
was  temporarily  dammed  up.  The  road  became  im- 
passable, and  a  new  road  was  constructed  across  the 
tremulous  mass,  with  fascines  and  faggots.  It  was 
a  frightful  scene,  to  behold  a  deep  valley  thus  filled 
up  with  a  mass  of  flowing  frozen  mire,  floating  enor- 
mous rocks  upon  its  surface,  and  which  contained 
scarce  any  water  except  in  a  solid  state.  [Ed.  Phil. 
Jour.  Oct.  1836,  p.  372.] 

On  the  28th.  Aug.  about  three  P.  M.  1823,  the 


In  what  year  did  the  fall  of  a  part  of  the  Dent  du  midi,  take 
place  ?  How  is  the  catastrophe  described  ?  When  did  the 
land  slip  in  Charaplain  occur  ? 


ALLUVIAL  DEPOSITS.  153 

inhabitants  of  the  village  Hayolle  in  the  parish  of 
Champlain,  (L.  C.)  were  alarmed  by  a  tract  of  land 
containing  a  superfices  of  207  arpents,  suddenly 
sliding  about  360  yards,  and  precipitating  itself  into 
the  Champlain  river,  which  it  dammed  «p  for  1300 
yards.  In  its  progress,  houses,  barns,  trees,  and 
whatever  lay  in  its  course,  were  overwhelmed.  The 
catastrophe  was  accompanied  by  an  appalling  sound ; 
arid  a  dense  vapour  filled  the  atmosphere,  oppressing 
those  who  witnessed  this  convulsion  almost  to  suffo- 
cation. A  man  who  was  on  the  ground  at  the  time, 
was  removed  with  it  to  a  considerable  distance,  and 
buried  up  to  the  neck,  but  was  extricated  from  his 
perilous  situation  without  having  sustained  serious 
injury.  [Quebec  Gazette,  and  Bost.  Jour.  Sc.  i. 
p.  301.] 

Glaciers  are  masses  of  snow  and  ice  more  or  less 
consolidated,  which  accumulate  above  the  limit  of 
perpetual  snow  on  high  mountains,  either  on  their 
summit  and  sides  or  in  the  valleys. 

The  appearance  of  the  mass  varies  according  to 
the  circumstances  under  which  it  was  formed.  If 
you  can  conceive  the  ocean  consolidated  when  roll, 
ing  its  swell  along  under  the  action  of  a  gentle  breeze, 
a  boundless  mirror  of  ice,  and  snow  drifts  magnified 
to  high  hills,  you  may  have  a  faint  idea  of  the  forms 
in  which  glaciers  are  presented  to  the  eye ;  "but 
nothing  less  than  the  actual  view  can  give  a  con- 
ception  of  the  amazement,  if  not  the  terror  with 


How  many  yards  did  it  slide  ?  What  is  further  said  of  it  ? 
What  are  Glaciers  ?  What  gives  a  faint  idea  of  the  forms 
in  which  glaciers  are  presented  to  the  eye  ? 


154  ALLUVIAL  DEPOSITS. 

which  the  appearance  is  first  beheld.  The  traveller 
stands  in  a  new  world,  surrounded  by  new  scenes  ; 
no  living  being  is  there,  and  no  sounds  but  his  own 
feeble  voice  and  the  thunder  of  the  tumbling  ava- 
lanches ;  not  a  flower  or  tree  can  be  seen  except  the 
lonely  pine,  which  seems  left  alone  to  mourn  over 
the  grave  of  nature." 

"  But  even  this  desolate  region  has  its  use  in  the 
economy  of  nature,  for  it  is  the  reservoir  of  those 
springs  which  distribute  fertility  through  the  valleys 
and  plains  ;  and  gives  that  in  gentle  streams  which 
would  otherwise  rush  headlong  in  its  fury  to  the 
valleys,  and  leave  ruin  and  desolation  in  its  path." 
[Phys.  Condition  of  the  Earth,  p.  339.] 

Biggsby  in  describing  the  geology  of  Lake  Huron, 
says :  In  the  spring  the  ice  removes  fragments  of 
great  size.  During  the  winter  it  surrounds  those 
which  are  placed  in  the  shallows,  and  on  being 
broken  up  by  the  mild  weather  of  spring,  by  the  rise 
of  water  which  takes  place  in  consequence  of  the 
blowing  of  the  wind,  they  are  either  carried  higher 
on  the  shore,  leaving  a  furrow  behind  them,  or  they 
are  moved  off  with  the  field  of  ice  to  which  they 
are  attached  ;  and  on  the  melting  of  the  ice  deposit- 
ed on  some  other  shore  more  or  less  distant  from 
their  original  situation.  Rolled  stones  of  some  yards 
in  diameter  are  thus  removed.  [Am.  Jour.  Sc.  iii. 
p.  256.] 

The  alluvial  deposits  projecting  into  the  sea,  and 


Of  what  use  are  glaciers  ?    What  is  said  respecting  the 
transporation  of  blocks  by  ice  ? 


ALLUVIAL  DEPOSITS.  155 

deposited  by  rivers,  are  called  deltas,  as  the  delta  of 
the  Nile,  of  the  Ganges,  of  the  Mississippi,  Rhone, 
Po,  Volga,  and  the  Danube.  The  delta  of  the 
Ganges  commences  220  miles  in  a  direct  line  from 
the  ocean. 

Adria,  which  was  once  a  port  on  the  Adriatic  sea, 
is  now  20  miles  inland.  The  waters  of  the  Ganges, 
and  Mississippi,  are  so  turbid,  when  in  flood,  as  to 
give  about  one  quarter  their  volumes  of  sediment. 

Rivers  which  project  their  deltas  into  the  sea, 
have  generally  a  tendency  to  raise  their  beds  in  the 
lower  part  of  their  course,  by  the  partial  deposit  of 
the  materials  brought  down.  This  is  more  particu- 
larly the  case  with  the  Po,  which  is  prevented  from 
overflowing  the  country  by  dykes.  The  bed  of  that 
river  has  risen  so  much  as  to  be  higher  than  the 
tops  of  the  houses  of  Ferrara.  In  Holland,  the  same 
phenomenon  is  observed,  but  not  on  so  great  a  scale. 
The  rivers,  in  fact,  run  in  a  canal  on  the  top  of  a  hill. 

Since  the  Mississippi  has  been  dyked,  the  same 
effect  may  be  perceived,  but  to  a  small  extent.  When 
sailing  along  the  Mississippi,  during  high  water, 
you  appear  to  be  above  the  surrounding  country ; 
the  dykes  appear  to  be  only  two  or  three  feet  high, 
but  on  landing,  you  observe  that  they  are  much 


What  are  deltas  ?  What  deltas  are  remarkable  ?  How 
far  does  the  delta  of  the  Ganges  commence  from  the  ocean  ? 
How  far  is  the  ancient  port  of  Adria  from  the  sea  ?  Are  the 
waters  of  any  rivers  very  turbid  ?  What  ones  are  particu- 
larly so  ?  What  tendency  have  rivers  which  project  deltas 
into  the  sea  ?  What  river  particularly  illustrates  this  fact  ? 
Is  the  same  effect  observed  in  other  places  ?  Does  the  Mis. 
sissippi  show  this  in  any  degree  ? 


156  ALLUVIAL  DEPOSITS. 

higher  on  the  land,  than  on  the  river  side.  The 
reason  is,  that  the  space  between  the  dyke  and  the 
river,  has  been  raised  by  deposits  from  the  river,  to 
a  height  equal  to  the  difference  of.level  between  the 
land  on  the  different  sides  of  the  dyke  ;  and  the  bed 
of  the  stream  rises  in  the  same  proportion  as  the 
banks. 

The  transporting  power  of  tides  and  currents  in 
the  ocean,  must  be  taken  into  consideration,  as  con- 
nected  with  alluvial  deposits.  Much  of  the  matter 
brought  down  by  rivers,  is  borne  away  by  tidal  cur 
rents.  These  currents  acting  on  the  shore,  in  con 
nection  with  the  waves,  remove  materials  from  one 
situation,  and  deposit  them  in  another. 

"  The  power  even  of  a  small  rivulet  when  swollen 
by  rain  was  lately  exemplified  in  the  College,  a 
small  stream  which  flows  with  a  moderate  declivity 
from  the  eastern  water  shed  of  the  Cheviot  hills. 
Several  thousand  tons  weight  of  gravel  and  sand 
were  transported,  to  the  plain  of  the  Till ;  and  a 
bridge  then  in  progress  of  building  was  carried 
away,  some  of  the  arch  stones  of  which,  weighing 
from  half  to  three-quarters  of  a  ton  each,  were  pro- 
pelled two  miles  down  the  rivulet.  On  the  same 
occasion  the  current  tore  away  from  the  abutment 
of  a  mill-dam  a  large  block  of  greenstone  porphyry, 
weighing  nearly  two  tons,  and  transported  it  to  the 
distance  of  a  quarter  of  a  mile.  Instances  are  men- 
tioned  as  occurring  repeatedly  in  which  from  1000 


Do  the  tides  and  currents  of  the  ocean  transport  alluvion  ? 
What  effects  were  produced  by  the  action  of  a  rivulet  when 
swollen  by  rain  ? 


ALLUVIAL  DEPOSITS.  157 

to  3000  tons  of  gravel  are  in  like  manner  removed 
to  great  distances  in  one  day."  [LyeE's  Geol.  i. 
p.  201.,  and  proceedings  Geol.  Soc.  Lond.  No.  xii. 
p.  829.] 

"  The  river  Don  has  forced  a  mass  of  400  or  500 
tons  of  stones  many  of  them  200  or  300  Ib.  weight, 
up  an  inclined  plane,  rising  6  feet  in  8  or  10  yards, 
and  left  them  in  a  heap  three  feet  deep  on  a  flat 
ground."  [Quar.  Jour.  N.  S.  xii.  p.  331.  LyeWs 
Prin.  of  Geol.  i.  p.  201.] 

When  the  materials  are  of  a  loose  nature,  like 
sand,  clay,  or  soft  rock,  the  wearing  away  of  the 
head-lands,  against  which  the  currents  beat,  is  very 
rapid,  but  if  pebbles,  or  other  hard  materials  be  con- 
tained  in  the  banks,  the  lighter  or  softer  materials 
are  removed,  and  the  hard  ones  gradually  form  a 
slope,  which  protects  the  shore  in  a  great  degree 
from  further  action. 

The  action  of  wind  in  transporting  materials  from 
one  situation  to  another,  is  more  important  than 
one  would  be  led  to  imagine,  without  a  knowledge 
of  facts. 

"  Extensive  tracts  of  cultivated  ground  are  some- 
times  converted  into  sandy  deserts,  by  the  drifting 
of  the  sea-sand  inland.  The  process  by  which  this 
is  effected,  is  taking  place  in  many  situations.  Dur- 
ing high  winds,  the  sand  is  driven  from  the  sea-shore 


What  is  said  of  the  force  of  the  river  Don  ?  Are  head- 
lands washed  rapidly  away  by  the  action  of  the  waves  and 
currents  ?  What  serves  finally  to  protect  them  from  further 
action  ?  Is  wind  ever  an  agent  in  transporting  alluvial  mat- 
ter ?  What  are  the  effects  produced  by  the  drifting  of  sand  ? 
How  is  the  process  effected  on  the  sea  shore  ? 
14 


158  ALLUVIAL  DEPOSITS. 

to  a  certain  distance,  leaving  an  elevated  ridge  at  the 
farther  boundary  of  the  drift.  Succeeding  winds 
blow  the  sand  forwards,  and  at  the  same  time  bring 
fresh  sand  from  the  shore  to  supply  its  place.  Trees, 
houses,  and  even  villages,  have  been  surrounded  and 
covered  with  sand,  in  some  parts  of  Ireland  and 
England,  within  the  last  century." 
.  Instances  of  these  encroachments  may  be  seen 
on  many  parts  of  our  own  coast.  A  particular  in- 
stance  of  a  light-house,  on  the  coast  of  Virginia, 
being  partly  covered,  and  the  bank  progressing  into 
the  country,  with  a  steep  front  of  twenty  or  thirty 
feet,  burying  trees  and  every  thing  else  in  its  course, 
is  described  in  the  American  Philosophical  Trans- 
actions,  Vol.  iv.  p.  439.,  and  is  well  worth  the  at- 
tention  of  the  curious  reader. 

It  is  well  known  that  a  considerable  portion  of 
Egypt  is  buried  by  the  sands  drifted  upon  it,  and 
that  the  Red  Sea  is  in  many  places  rendered  quite 
shoal  by  coral  reefs,  and  by  the  sand  drifted  into  it. 
The  sand-storms  of  the  deserts,  have  often  been 
described. 

During  the  expedition  of  Gen.  Atkinson  to  the 
Yellow  Stone  River,  in  1825,  a  forest  of  petrified 
trees  was  observed,  standing  erect,  but  with  their 
smaller  limbs  broken  off,  and  scattered  on  the  sandy 
desert  beneath  them.  They  had  probably  been  ori- 
ginally covered  by  sand,  drifted  over  them  either  by 
wind  or  by  water,  and  remained  thus  long  enough 


Are  houses,  or  villages,  ever  buried  ?  What  is  said  of  the 
light  house  in  Virginia  ?  What  is  said  of  Egypt,  and  of  the 
Red  Sea  ?  What  is  said  of  the  petrified  forest  ? 


ALLUVIAL  DEPOSITS.  159 

to  become  petrified.  The  loose  sand  appears  after- 
wards to  have  been  drifted  away  by  the  wind,  leav- 
ing them  monuments  of  the  changes  of  the  earth's 
surface. 

Shoals  often  become  sensibly  more  shallow,  by  the 
combined  effects  of  shell-fish,  and  other  marine  ani- 
mals, living,  growing,  and  afterwards  leaving  their 
remains  as  a  basis  for  others  to  live  and  die  upon 
successively.  Coral  reefs  are  produced  in  such 
abundance  in  some  parts  of  the  Pacific  and  Indian 
oceans,  as  to  obstruct  the  navigation,  although  the 
animals  employed  in  building  them  are  so  small  as 
to  be  hardly  visible  to  the  naked  eye. 

Mr.  Uobert  in  his  account  of  the  geology  of 
Iceland,  mentions  that  in  the  vicinity  of  the  gey- 
sers, tho  silicious  concretionary  deposits,  form  a 
mass  no  less  than  4  leagues  in  length.  \_Ed  Phil. 
Jour.  Oct.  1836.  p.  372.] 

Peat  is  a  substance  generally  classed  with  allu- 
vial soils,  although  it  is  a  vegetable  production. 

Peat  is  generally  situated  in  low,  wet  grounds, 
but  is  sometimes  found  on  the  declivities  of  moun- 
tains. The  condition  that  seems  to  be  essential  to 
the  formation  of  peat,  is,  that  the  soil  should  not  be 
permeable,  and  that  the  water  which  covers  it  should 
be  neither  stagnant,  nor  too  rapidly  renewed;  and 
that  the  vegetables  should  not  rot,  but  experience  a 


What  explanation  is  offered  of  this  phenomenon  ?  What 
is  said  o.-'  shoals?  Are  coral  reefs  common?  How  large 
are  the  animals  that  build  these  reefs?  What  is  peat? 
Where  \-.\  peat  generally  situated  ?  What  condition  seems 
essential  to  its  formation  1 


160  ALLUVIAL  DEPOSITS. 

peculiar  change  anologous   to   tanning.     [Brong- 
niart  Tableau  des  Terr  airs,  p.  37.] 

Peat  is  rarely  found  in  the  tropics,  but  abounds  in 
most  cold  climates.  It  is  said  that  Ireland  has  one- 
tenth  of  its  surface  covered  with  peat.  In  the 
Northern  States  of  the  United  States  it  is  very 
abundant,  in  the  South,  and  Southwestern  it  is  rare- 
ly seen.  The  organic  matters  that  in  a  favourable 
location  would  give  rise  to  peat,  are  destroyed  by 
insects,  or  by  putrefaction. 

Peat  meadows  generally  exhibit  a  wet,  spongy 
surface,  and  when  capable  of  supporting  much 
weight,  its  surface  will  shake  and  tremble  for 
some  distance  around,  by  walking  or  jumping  upon 
it.  Good  peat  cuts  easily  and  clear  with  the  spade ; 
but  if  it  resist  the  spade  with  a  degree  of  elasticity, 
it  is  found  to  be  less  compact  when  dry,  and  of  an 
inferior  quality.  The  best  kinds,  burn  with  a  clear 
flame,  leaving  light  colored  ashes  ;  but  the  poorer 
kinds  often  emit  a  disagreeable  smell,  and  leave  a 
heavy,  red-colored  ash. 

"  The  process  by  which  the  mosses  are  converted 
into  peat,  is  clearly  seen  in  one  of  them,  (the  sphag- 
num palustre.)  As  the  lower  extremity  of  the  plant 
dies,  the  upper  sends  forth  fresh  roots,  like  most  of 
the  mosses,  the  individual  thus  in  a  manner  becom- 
ing immortal,  and  supplying  a  perpetual  fund  of  de- 
composing vegetable  matter.  A  similar  process, 

What  is  the  proportion  of  peat  in  Ireland  ?  What  is  the 
appearance  of  peat  meadows  ?  If  you  walk  or  jump  on  them, 
what  is  observed  ?  What  are  the  characters  of  good  peat  ? 
How  can  you  distinguish  the  good  from  that  of  inferior 
quality  ?  Explain  the  formation  of  peat  ? 


TRAP  ROCKS.  163 

perpendicular  cliffs  of  several  hundred  feet  in 
height. 

In  the  sketch  above,  columnar  trap  is  represented 
as  r ;  sting  unconformably,  on  inclined  strata.  A  dyke 
of  the  same  kind  of  rock  is  shewn,  cutting  through 
the  other  rocks,  and  a  bed  connected  with  the  dyke 
lying  between,  and  separating  them.  "  It  is  obvious 
that  these  unconformable  rocks  were  formed  and  de- 
posited at  a  subsequent  period  to  that  in  which  the 
lower  rocks  were  consolidated,  and  their  beds  had 
acquired  their  present  inclined  positions." 

The  term  trap  is  derived  from  the  Swedish  word 
trappa,  a  stair,  because  these  rocks  often  divide  into 
regular  forms  resembling  the  steps  of  a  stair.  These 
rocks,  composed  of  feldspar  and  hornblende,  or  of 
hornblende  and  augite,  are  called  greenstone,  sienitic 
greenstone,  basalt,  clinkstone,  pitchstone,  amygda- 
loid, wacke,  ancT  porphyry. 

Greenstone  is  essentially  composed  of  feldspar 
and  hornblende,  in  the  state  of  grains  or  small  crys- 
tals, the  proportions  varying,  but  the  hornblende 
generally  predominates.  The  grains  are  sometimes 
so  small  that  the  different  minerals  cannot  be  dis- 
tinguished from  each  other.  The  rock  derives  its 
name  from  its  being  frequently  of  a  greenish  color, 
especially  when  moistened.  When  fine  grained  it 
generally  exhibits  a  columnar  structure,  as  in  the 
East  and  West  rocks  near  New  Haven,  and  the 


At  what  period  were  these  rocks  deposited  ?  From  what 
is  the  term  trap  derived  ?  Describe  greenstone  ?  Does  it 
ever  show  the  columnar  structure  ?  Where  may  this  be  ob- 
served? 


164  TRAP  ROCKS. 

Palisades  on  the  Hudson  river,  and  Mount  Holyoke, 
near  Northampton,  Mass. 

Greenstone  is  sienitic  when  it  is  coarse  grained, 
and  becomes  sienite  when  feldspar  predominates. 
Basalt  is  a  compact,  homogenous  mass  of  rock  com- 
posed of  feldspar  and  hornblende  or  augite.  It  has 
a  greenish  or  brownish  black  color,  and  is  very 
tough  or  difficult  to  break,  but  can  be  scratched  with 
the  point  of  a  knife. 

It  melts  easily  into  a  black  or  dark  green  glass, 
and  is  extensively  used  in  France,  for  the  manufac- 
ture of  glass  bottles.  The  iron  contained  in  it,  is, 
by  exposure  to  the  weather,  further  oxidized,  and 
causes  the  yellowish  or  brownish  red  colour  that  it 
usually  presents  on  its  surface. 

When  basalt  is  slaty,  or  the  feldspar  predomin- 
ates, it  becomes  clinkstone:  when  earthy  in  its 
texture  and  mixed  with  green  earth,  it  is  called 
wacke.  When  basalt  or  wacke  contain  rounded 
cavities  entirely  or  partly  filled  with  other  miner- 
als, they  form  amygdaloid.  Basalt  is  generally 
columnar  in  its  form,  but  sometimes  is  seen  in  large 
tabular,  or  in  globular  masses.  The  general  aspect 
of  the  trap  rocks  where  they  form  large  masses,  is 
such  as  at  once  to  attract  the  attention  of  the 
traveller. 

The  porphyry  and  basalt  on  the  Andes,  says  Hum- 
bolt,  "are  arranged  in  regular  columns,  which  strike 

Describe  basalt  ?  For  what  is  it  used  ?  What  change  is 
observed  in  its  appearance  when  long  exposed  to  the  weather  ? 
What  is  clinkstone  ?  What  is  amygdaloid  ?  Is  basalt  colum- 
nar ?  What  is  the  general  aspect  of  the  trap  rocks  ?  What 
is  said  of  the  porphyry  and  basalt  of  the  Andes  ? 


TRAP  ROCKS.  161 

though  less  distinct,  takes  place  in  many  of  the 
rushes  and  grasses,  the  ancient  roots  dying  together 
with  the  older  leaves  ;  while  an  annual  renovation 
of  both,  perpetuates  the  existence  of  the  plant. 
Where  the  living  plant  is  still  in  contact  with  peat, 
the  roots  of  the  rushes  and  ligneous  vegetables  are 
found  vacillating  between  life  and  death,  in  a  spon- 
gy, half  decomposed  mass.  Lower  down,  the  pul- 
verized carbonaceous  matter  is  seen  mixed  with 
similar  fibres,  still  resisting  decomposition.  These 
gradually  disappear,  and  at  length,  a  finely  powder- 
ed substance  alone  is  found ;  the  process  being  com- 
pleted by  the  total  destruction  of  all  organized  bo- 
dies." "  The  best  peat  is  that  of  which  the  decom- 
position is  most  complete,  and  the  specific  gravity 
and  compactness,  the  greatest." — [Bakewell's  Geo- 


CHAPTER  XII. 
TRAP  ROCKS. 

All  the  REGULAR  classes  of  rocks  have  now  been 
considered  ;  that  is,  all  the  rocks  that  are  superpos- 
ed one  above  the  other,  in  a  regular  order  of  super- 
position. It  must  not,  however,  be  inferred,  that  the 
rocks  are  all  present  in  every  situation.  Some  of 
them  are  absent  from  almost  every  locality  :  but 
where  two  or  more  of  them  occur  together,  they  are 

Are  all  the  classes  of  rock  present  in  every  locality  ?  Where 
any  two  of  them  occur  together,  how  are  they  laid  upon  each 
ether? 

14* 


162 


TRAP  ROCKS. 


laid  over  each  other  in  the  order  in  which  they 
have  been  described.  For  instance,  the  coal  forma- 
tion, wherever  it  is  found,  lies  above  the  primitive 
rocks,  and  if  the  transition  rocks  be  present,  it  lies 
above  them  also.  If  the  transition  rocks  be  absent,  the 
coal  formation  rests  on  the  primitive  rocks,  as  is  the 
case  with  the  coal  near  Richmond  in  Virginia. 

Diluvial  and  alluvial  deposits  often  rest  on  the 
primitive  rocks,  all  the  other  classes  being  absent ; 
but  these  deposits  are  never  found  under  the  transi- 
tion, secondary,  or  tertiary  rocks. 

Two  more  classes  of  rocks  remain  to  be  describ- 
ed, which  have  no  regular  situation  in  connection 
with  the  other  rocks,  but  are  distributed  in  beds  and 
masses  indiscriminately  among  them.  They  are 
called  Trap  and  volcanic  rocks. 

Trap  rocks  are  mostly  composed  either  of  horn- 
blende and  feldspar,  or  augite  and  feldspar.  "  These 
rocks  although  they  sometimes  occur  imbedded  in 
the  conformable  rocks,  more  frequently  cover  them 
in  an  unconformable  position,  composing  thick,  un- 
stratified  beds,  and  often 
mountain  masses  of  vast 
size,  which  have,  not  un- 
frequently,  a  columnar 
structure,"  and  present 

For  instance,  is  the  coal  formation  ever  found  below  primi- 
tive rocks?  Is  it  ever  found  lying  upon  primitive  rocks? 
Do  the  alluvial  and  diluvial  deposits  ever  rest  directly  upon 
the  primitive  rocks  ?  Are  these  deposits  ever  found  under 
the  secondary,  transition,  or  tertiary  rocks  ?  Of  what  are 
trap  rocks  mostly  composed  ?  Do  these  rocks  rest  conform, 
ably  upon  the  others  ?  What  structure  do  these  rocks  often 
have  ?  Does  trap  ever  occur  imbedded  conformably  in  other 
rocks  ? 


TRAP  ROCKS.  165 

the  eye  of  the  traveller  like  immense  castles  lifted 
into  the  sky."  "  Were  it  allowed  to  express  a  geo- 
logical fact  in  familiar  terms,  it  might  be  said  that 
all  the  members  of  the  trap  family  give  indications 
of  a  fiery  character,  and  of  having  been  trouble- 
some neighbours  to  the  adjacent  rocks,  disturbing 
them  and  even  changing  their  nature,  when  they 
are  closely  associated.  Besides  occurring  in  over- 
lying unconformable  masses,  all  trap  rocks  with 
porphyry,  which  may  be  placed  at  their  head,  are 
occasionally  found  intersecting  other  rocks  like  ver- 
tical walls." 

Walls  and  dykes  are  synonymous  in  some  parts 
of  England,  from  which  these  veins  of  trap  rocks 
take  their  name.  The  substance  of  dykes  is  gene- 
rally basalt.  Dykes  have  been  very  much  studied, 
on  account  of  their  cutting  through  the  coal  fields 
in  various  directions,  and  causing  great  derange- 
ment in  the  positions  of  the  strata. 

This  derangement  has  been  referred  to  in  the 
chapter  on  stratification.  Dykes  vary  in  thickness 
from  a  few  inches  to  several  hundred  feet.  "The 
extent  to  which  they  stretch  across  a  country  has 
seldom  been  explored  beyond  the  mining  districts, 
where  a  knowledge  of  them  is  important,  on  account 
of  the  disturbances  which  they  occasion  in  the  stra- 
ta." "  The  strata  are  almost  always  thrown  down 
on  one  side  of  a  dyke,  and  elevated  on  the  other,  but 
the  dislocation  is  not  proportioned  to  its  breadth." 
"  Trap  dykes  are  generally  harder  than  the  rocks 


What  is  the  effect  of  trap  dykes  on  the  strata  ?     Do  basaltic 
dykes  ever  appear  above  the  surface  of  the  earth  ? 


166  TRAP  ROCKS. 

that  they  intersect;  and  when  the  latter  are  partial- 
ly decomposed,  often  remain,  forming  vast  walls  of 
stone  that  rise  above  the  surface  of  the  ground." 

Walls  of  this  kind  extend  for  miles  along  the 
country  in  some  parts  of  England.  They  extend 
into  the  sea,  forming  reefs  of  rocks,  and  across  riv- 
ers, making  falls  or  fords.  The  natural  walls  of 
North  Carolina  are  basaltic  dykes,  formed  of  co- 
lumnar or  prismatic  mass- 
es fitting  close  to  each 
other,  and  lying  with  their 

lengths  across  the  wall,  and 

shewing  their  ends  on  its  sides,  as  represented  in  the 
sketch. 

When  these  walls  were  first  observed,  they  were 
supposed  to  be  artificial  constructions,  from  the  re- 
gularity of  form  of  the  separate  pieces."  "Dykes 
being  impervious  to  water,  they  obstruct  its  passage 
along  the  porous  strata,  and  occasion  it  to  rise  ; 
hence  it  frequently  happens  that  numerous  springs 
make  their  appearance  along  the  course  of  a  dyke, 
by  which  it  may  be  detected  when  there  is  no  other 
indication  of  it  visible  upon  the  surface." 

The  effects  of  basaltic  dykes  on  the  different 
rocks  through  which  they  pass,  are  worthy  of  re- 
mark. There  is  one  basaltic  dyke  in  England  that 
has  been  traced  70  miles,  and  intersects  various 


Are  these  natural  walls  of  any  great  extent  ?  Have  they 
been  observed  in  the  United  States  ?  By  what  appearance 
on  the  surface  may  dykes  be  recognized,  when  they  are  not 
visible  ?  What  are  the  effects  of  the  great  basaltic  dyke  of 
England,  upon  the  transition  rocks,  and  upon  the  coal  through 
which  it  passes  ? 


TRAP  ROCKS.  167 

strata  of  rocks  of  different  ages.  Where  it  is  in 
contact  with  transition  limestone,  the  latter  is  more 
crystalline,  a  fact  of  geological  importance.  "  Where 
it  crosses  the  coal  strata  and  comes  in  contact  with 
the  seams  of  coal,  the  substance  of  the  coal  for  sev- 
eral feet  is  converted  into  soot.  At  a  greater  dis- 
tance from  the  basalt,  the  coal  is  reduced  to  a  coke 
or  cinder,  which  burns  without  smoke,  and  with  a 
clear  and  durable  heat.  At  the  distance  Of  fifty 
feet  from  the  dyke,  the  coal  is  found  in  its  natural 
unaltered  state.  It  is  particularly  remarkable,  that 
the  roof  immediately  above  the  coal  is  covered  with 
bright  crystals  of  sulphur.  Dykes,  when  they  cut 
through  chalk,  convert  it  into  a  highly  crystalline 
limestone,  where  these  rocks  come  in  contact. 
Shale  is  changed  to  a  flinty  slate,  and  sandstones 
become  of  a  brick  red  colour." 

It  may  be  well  to  mention  some  experiments  that 
have  been  made,  which  serve,  in  some  degree,  to 
elucidate  the  probable  mode  of  formation  of  the  trap 
rocks. 

"  All  trap  rocks  are  fusible,  *  and  most  of  them 
form  a  blackish  green  glass  after  melting  :  hence  it 
was  inferred,  that  trap  rocks  had  never  been  in  a 
state  of  fusion,  for  if  they  had  they  would  have  been 
rendered  vitreous,  f  * 

Sir  James  Hall,  however,  reflecting  on  the  very 

What  crystals  are  attached  to  the  roof?  What  are  th? 
effects  of  basaltic  dykes  on  chalk,  shale  and  sandstones,  when 
they  intersect  them  ? 

*  Bodies  are  said  to  be/tm&Ze,  when  they  can  be  melted, 
t  Bodies  are  said  to  be  vitreous,  when  they  break  with  a  smooth 
surface  like  glass. 


168  TRAP  ROCKS. 

long  period  of  refrigeration*  that  vast  masses  of 
melted  rock  would  necessarily  require  before  they 
were  cooled  to  the  common  temperature  of  the  earth, 
was  induced  to  make  experiments  on  lava  and  ba- 
salt ;  from  which  it  was  ascertained,  that  if  a  small 
portion  of  liquid  lava  were  suddenly  cooled,  it  form- 
ed  a  black  glass,  as  was  well  known  to  be  the  case 
with  basalt ;  but  if  the  process  of  cooling  were  slow, 
both  melted  lava  and  basaltic  became  stone.  When 
the  glass  which  had  been  formed  by  sudden  cooling 
was  melted  again,  and  suffered  to  cool  very  gra- 
dually, it  lost  its  vitreous  character,  and  was  con- 
verted into  a  substance  resembling  basalt. 

Mr.  Gregory  Watt  made  some  experiments  on  the 
fusion  and  refrigeration  of  basalt  in  one  of  his  father's 
furnaces,  which  throws  much  additional  light  on  the 
formation  of  the  globular  and  columnar  structure  of 
basaltic  rocks.  He  fused  700  Ibs.  of  the  Dudley 
basalt,  called  Rowley  ragg,  and  kept  it  in  the  fur- 
nace several  days  after  the  fire  was  reduced.  It 
melted  into  a  dark  coloured  glass,  with  less  heat 
than  was  necessary  to  melt  the  same  quantity  of  pig 
iron.  In  this  glass,  small  globules  were  formed 
which  afterwards  disappeared ;  and  as  the  cooling 
proceeded  the  mass  was  changed  from  a  vitreous  to 
a  stony  substance  :  other  globes  were  again  formed 
within  the  stony  mass,  which  continued  to  enlarge 
until  their  sides  touched  and  pressed  against  each 


What  experiments  have  been  made  which  tend  to  eluci. 
date  the  formation  of  trap  rocks  ? 

*  Refrigeration  means  the  cooling  of  a  body. 


TRAP  ROCKS.  169 

other,  by  which  pressure  the  globes  formed  poly, 
gonal*  prisms. f  If  part  of  the  mass  were  cooled 
before  the  globular  structure  was  destroyed,  these 
globes  were  harder  than  the  surrounding  stone,  and 
broke  in  concentric  layers.  In  this  manner  the 
balls  of  basalt  and  porphyry  which  fall  out  of  decom- 
posing rocks  were  probably  formed :  they  derived 
their  superior  hardness  from  the  crystalline  arrange- 
ment of  the  particles  when  in  a  melted  state.  When 
these  globes  were  enlarged  by  a  continuation  of  the 
same  process,  they  might  press  upon  each  other  and 
form  prisms.  The  upper  prisms,  pressing  by  their 
weight  upon  the  lower,  might  form  conca- 
vities, or  sockets,  into  which  they  would  sink 
and  remain  jointed,  or  articulated  together  : 
such  is  frequently  the  structure  of  basaltic 
columns,"  thus — 

"  Another  experiment  made  by  Sir  James 
Hall,  on  the  crystallization  of  common  limestone  by 
heat,  and  its  conversion  into  marble,  tends  to  eluci- 
date the  effects  produced  by  basaltic  rocks  on  lime- 
stone and  chalk,  before  mentioned.  Dr.  Hutton  had 
advanced  the  opinion,  that  the  beds  of  limestone 
were  formed  of  the  shells  and  exuviae  of  marine  ani- 
mals, which  had  been  melted  by  central  fire,  and 
crystallized."  * 

"  It  was,  however,  objected  to  this  theory,  that  the 
well  known  action  of  fire  on  limestone  rocks  would 


*  A  polygon  is  a  figure  having  several  sides  :  for  instance,  a  square 
is  a  polygon  of  four  sides. 

t  A  prism  is  a  solid  body  having  seversl  sides,  and  of  equal  size  from 
one  end  to  the  other :  for  instance,  the  beams  and  posts  of  buildings 
are  four-sided  prisms,  A  prism  may  have  any  number  of  sides  above 
tbree. 

15 


170  TRAP  ROCKS. 

expel  the  carbonic  acid,  and  make  them  soft  and  pul- 
verulent, as  we  see  in  making  lime  from  limestone. 

This  objection  was  answered,  by  saying,  that  these 
beds  of  shells,  &c.  were  heated  under  the  pressure 
of  the  ocean  which  for  so  long  time  covered  the  land, 
and  that  this  pressure  would  prevent  the  escape  of 
the  carbonic  acid,  and  render  the  limestone  fusible. 
This  was  regarded  as  mere  hypothesis  for  some  time, 
but  Sir  James  Hall  determined  to  try  its  validity  by 
experiments." 

Having  calculated  the  resistance  which  a  column 
of  water,  1500  feet,  or  any  given  depth,  would  pre- 
sent to  the  escape  of  the  carbonic  acid  of  the  lime- 
stone, he  inclosed  a  quantity  of  powdered  chalk  in 
a  gunbarrel,  and  confined  it  in  such  a  manner  as  to 
present  an  equal  degree  of  resistance.  He  subjected 
the  powdered  chalk,  thus  confined,  for  some  time  to 
the  action  of  a  furnace  ;  it  was  then  drawn  out  and 
cooled,  and  was  found  converted  into  crystalline  lime- 
stone or  marble ;  and  in  one  instance  whe^e  the 
chalk  inclosed  a  shell,  the  shell  had  acquired  a  crys- 
talline texture  without  loosing  its  form.  Hence, 
when  chalk  or  limestone  is  found  to  have  a  crystal- 
line texture  in  contact  with  trap  rocks,  we  may, 
with  a  high  degree  of  probability,  infer  that  the 
limestone  had  been  fused  by  the  trap. 

"The  constant  occurrence  of  dykes  in  basaltic 
districts,  gives  a  high  degree  of  probability  to  the 
opinion,  that  overlying  unconformable  trap  rocks 
have  been  erupted  in  a  melted  state  like  lava,  and 


What  is  supposed  to  have  been  the  origin  of  the  uncoil- 
formable  overlying  trap  rocks  1 


TRAP  ROCKS.  171 

poured  over  the  surface  of  the  ground."  Basaltic 
columns  are  frequently  seen  in  countries  that  are 
the  seat  of  volcanic  fires,  but  they  occur  also  in 
countries  remote  from  any  known  volcanos. 

Organic  remains  are  sometimes  found  enveloped 
in  basalt,  but  this  admits  of  an  easy  explanation,  by 
supposing  the  basalt  to  have  flowed  like  lava  on  th'e 
bottom  of  the  ocean,  enclosing  every  thing  with 
which  it  came  in  contact.  A  recapitulation  of  all 
the  facts  bearing  upon  the  origin  of  the  trap  rocks, 
would  afford  a  mass  of  evidence  sufficient  to  con- 
vince the  most  sceptical,  of  their  igneous  origin. 

"  The  reason  why  geologists  were  so  long  opposed 
to  the  igneous  origin  of  trap  rocks,  may  partly  be 
explained  by  attachment  to  received  theories,  and 
partly  by  the  reluctance  to  admit  a  condition  of  our 
planet,  so  remote  from  present  experience.  It  was 
thought  an  ample  claim  on  our  credulity,  when 
we  were  required  to  believe  that  all  the  habitable 
parts  of  the  globe  had  been  for  ages  submerged  in 
the  ocean,  without  requiring  the  further  belief,  that 
countries  now  remote  from  active  volcanos,  had 
been  repeatedly  subject  to  the  agency  of  subter- 
ranean fire.  Yet  both  these  positions  must  be  grant- 
ed, if  we  will  allow  a  legitimate  induction  from  es- 
tablished facts."  [BakeweWs  Geology.'] 

Are  basaltic  columns  often  found  in  volcanic  districts  ? 
Are  organic  remains  ever  enclosed  in  basalt  ?  How  is  this 
fact  explained  ?  What  conclusions  must  be  drawn  jf  we 
allow  a  legitimate  induction  from  established  facts. 


172  EARTHQUAKES,  &C. 


CHAPTER  XIII. 

EARTHQUAKES,  VOLCANIC  PHENOMENA,  AND  VOL- 
CANIC ROCKS. 

"  Accustomed  to  view  the  hills  in  our  own  coun- 
try in  a  state  of  profound  repose,  presenting  the  same 
unvaried  outline  in  each  succeeding  year,  we  can 
scarcely  conceive  the  possibility  of  a  whole  district 
being  covered  with  new  mountains,  and  another  soil, 
in  the  space  of  a  single  night :  yet  such  changes 
have  been  produced,  by  the  united  agency  of  earth- 
quakes and  volcanos,  within  the  limits  of  authentic 
history." 

Earthquakes  seem  to  be  mere  vibrations  of  the 
crust  of  the  globe,  when  rent  and  upheaved  by  vol. 
canic  action.  Earthquakes  and  volcanos  seem  to 
be  the  effect  of  the  same  cause.  They  frequently 
accompany  each  other,  and  in  all  instances  that 
have  been  observed,  the  first  eruption  of  a  volcano 
is  preceeded  by  an  earthquake  of  greater  or  less  ex- 
tent. 

Volcanos  do  not  make  their  appearance  in  every 
country  where  the  shock  of  an  earthquake  is  felt ; 
but  earthquakes  are  more  frequent  in  volcanic  dis- 
tricts than  in  any  other.  Earthquakes  are  almost 


What  are  earthquakes?  Do  earthquakes  and  volcanos 
ever  accompany  each  other  ?  and  do  they  depend  upon  the 
same  cause?  In  what  districts  do  earthquakes  most  fre- 
quently occur  ?  What  are  earthquakes  almost  always  pre- 
ceded by  ? 


EARTH QITAKES,  &C.  173 

always  preceded  by  an  uncommon  agitation  of  the 
waters  of  the  ocean,  and  of  lakes.  Springs  send 
forth  torrents  of  mud,  accompanied  by  a  disagree- 
able smell ;  or  perhaps  they  disappear  entirely.  The 
cattle  discover  much  alarm,  and  seem  to  be  instinc- 
tively aware  of  approaching  calamity. 

A  deep  rumbling  noise  like  that  of  many  carriages 
rolling  over  a  rough  pavement,  a  rushing  sound  like 
the  wind,  or  a  tremendous  explosion  like  the  dis- 
charge of  artillery,  immediately  precede  the  shock, 
which  suddenly  heaves  the  ground  upwards,  or  tosses 
from  side  to  side  with  violent  and  successive  vibra- 
tions. The  ground  often  heaves  in  undulations  like 
the  waves  of  the  ocean  :  large  chasms  and  fissures 
are  made  in  the  ground,  through  which  smoke  and 
flames  are  seen  to  issue  :  these  sometimes  break  out 
where  no  chasms  can  be  perceived.  More  frequent- 
ly, stones  or  torrents  of  water  are  ejected  from  these 
openings. 

In  violent  earthquakes,  the  chasms  are  so  exten- 
sive, that  large  cities  have  in  a  moment  sunk  down 
and  forever  disappeared,  leaving  a  lake  of  water  in 
their  place.  Such  was  the  fate  of  Euphemia  in 
Calabria,  in  1638,  as  described  by  Kircher  who  was 
approaching  the  place,  when  the  agitation  of  the 
ocean  obliged  him  to  land  at  Lopizicum.  , 

"  Here,  (says  he,)  scenes  of  ruin  every  where  ap- 
peared around  me ;  but  my  attention  was  quickly 
turned  from  remote  to  more  contiguous  danger,  by 

What  noise  is  perceived  before  an  earthquake  ?  How  is 
the  ground  affected  ?  Are  the  chasms  produced  by  earth- 
quakes ever  very  extensive  ? 

15* 


174  EARTHQUAKES,  &C. 

a  deep  rumbling  sound  which  every  moment  grew 
louder.  The  place  where  we  stood  shook  most 
dreadfully :  after  some  time,  the  violent  paroxysm 
ceasing,  I  stood  up,  and  turning  my  eyes  to  look  for 
Euphemia,  saw  only  a  frightful  black  cloud.  We 
waited  till  it  had  passed  away,  when  nothing  but  a 
dismal  and  putrid  lake  was  to  be  seen  where  the  city 
once  stood." 

A  shock  rarely  lasts  more  than  a  minute,  but  often 
there  is  a  succession  of  shocks,  with  intervals  of 
some  duration. 

"  The  extent  to  which  earthquakes  produce  sen- 
sible effects  on  the  waters  and  springs  in  distant 
parts  of  the  world,  is  truly  remarkable. 

During  the  earthquake  of  Lisbon,  in  1755,  almost 
all  the  springs  and  lakes  in  England,  and  every  part 
of  Europe,  were  violently  agitated,  many  of  them 
throwing  up  mud  and  sand,  and  emitting  a  fetid 
odour.  On  the  morning  of  the  earthquake,  the  hot 
springs  of  Toplitz  in  Bohemia,  suddenly  ceased  to 
flow  for  a  minute,  and  then  burst  forth  with  prodi- 
gious violence,  throwing  up  turbid  water,  the  tem- 
perature of  which  was  higher  than  before,  and  is 
said  to  have  continued  so  ever  since.  The  hot  baths 
at  Bristol,  England,  were  coloured  red,  and  rendered 
unfit  for  use,  for  some  time  afterward.  The  waters 
of  Lake  Ontario  were  violently  agitated  at  the  same 
time," 

The  space  over  which  the  vibration  of  the  earth 


How  long  do  the  shocks  continue  ?  Do  they  ever  rapidly 
succeed  each  other  ?  Are  earthquakes  ever  felt  over  exten- 
sive portions  of  the  globe  ? 


EARTHQUAKES,  &C.  175 

is  ielt  during  earthquakes,  is  often  very  great,  but 
generally  more  extended  in  one  direction  than  ano- 
ther ;  "  and  where  a  succession  of  earthquakes  has 
taken  place  in  the  same  districts,  it  is  observed  that 
the  noise  and  shock  approach  from  the  same  quarter." 

Although  earthquakes  are  more  common  in  vol. 
canic  districts  than  in  others,  yet  the  shocks  are  not 
the  most  violent  in  the  vicinity  of  volcanos  ;  on  the 
contrary,  they  are  stronger  in  the  more  distant  part 
of  a  volcanic  country.  The  ground,  generally,  is 
agitated  with  greater  force,  as  the  surface  has  a 
smaller  number  of  apertures  communicating  with 
the  interior. 

Extensive  earthquakes  are  sometimes  attended  by 
volcanic  action  simultaneously  in  various  parts  of 
the  earth,  which  seems  to  indicate  a  .cause  deep 
seated,  and  of  such  a  nature  as  to  be  capable  of 
transmitting  the  vibrations  and  pressure,  from  one 
portion  of  the  earth  to  another  with  great  rapidity. 

"  The  frequency  of  earthquakes  at  particular  pe- 
riods, is  worthy  of  notice.  In  the  4th  and  5th  cen- 
turies, some  of  the  most  civilized  parts  of  the  world 
were  almost  desolated  by  these  awful  visitations. 
Thrace,  Asia  Minor,  and  Syria,  according  to  cotem- 
porary  historians,  suffered  most  severely  :  the  earth, 
was  agitated  continually  for  long  periods,  and  flames 
were  seen  to  burst  forth  from  the  earth  over  a  vast 
extent  of  surface. 

On  the  26th  of  January,  A.  D.  447,  subterranean 


Are  the  shocks  as  violent  in  volcanic  districts  as  in  others  ? 
Have  earthquakes  been  more  frequent  at  particular  periods 
than  at  others  ? 


176  EARTHQUAKES,  &C. 

thunders  were  heard  from  the  Black  to  the  Red  Sea, 
and  the  earth  was  convulsed  without  intermission  for 
the  space  of  six  months :  in  many  places  the  air 
seemed  to  be  on  fire — towns  and  large  tracts  of 
ground  were  swallowed  up  in  Phrygia. 

On  the  20th  of  May,  A.  D.  520,  the  city  of  An- 
tioch  was  overturned  by  a  dreadful  earthquake,  and 
250,000  of  its  inhabitants  are  said  to  have  been 
crushed  in  its  ruins.  A  raging  fire  covered  the 
ground  on  which  the  city  was  built,  and  the  district 
around,  spreading  over  an  extent  of  forty-two  miles 
in  diameter,  and  a  surface  of  1400  square  miles." 

"  About  the  middle  of  the  last  century,  after  the 
earthquake  at  Lisbon,,  in  1755,  Europe,  Africa  and 
America,  were  for  some  time  repeatedly  agitated  by 
subterranean  explosions.  Mount  ^Etna,  which  had 
been  in  a  state  of  profound  repose  for  eighty  years, 
broke  out  with  great  activity ;  and,  according  to 
Humboldt,  some  of  the  most  tremendous  earthquakes 
and  volvanic  eruptions  ever  recorded  in  history, 
were  witnessed  in  Mexico. 

In  the  night  of  the  19th  of  September,  1759,  a 
vast  volcano  broke  out  in  a  lofty  cultivated  plain," 
in  Mexico.  A  tract  of  ground  about  4  miles  square 
swelled  up  like  a  bladder  to  a  height  of  524  feet,  and 
in  the  centre  of  a  thousand  burning  cones  six  large 
masses  elevated  themselves,  forming  hills  more  than 
1200  feet  in  height.  The  most  elevated  of  these  six 
mountains  is  1695  feet  high,  and  is  known  as  the 
volcano  of  Jorullo.* 


*  During  an  earthquake  in  1822,  100  miles  in  length  of  the  east  coast 
of  Chili,  in  South  America,  was  raised  from  3  to  4  feet  above  its  for-      ' 
mer  level.    The  whole  space  from  the  sea  to  the  mountains  was  rais-     \ 


EARTHQUAKES,  &C.  177 

"More  recently  (in  1812)  the  tremendous  earth- 
quakes in  Caraccas  were  followed  by  an  eruption 
in  the  Island  of  St.  Vincents,  from  a  volcano  that 
had  not  been  burning  since  the  year  1718,  and  vio- 
lent oscillations  of  the  ground  were  felt,  both  in  the 
islands  and  on  the  coasts  of  America."  It  was  at 
this  time  that  earthquakes  were  so  violent  in  the 
valley  of  the  Mississippi. 

"In  very  violent  earthquakes,  the  secondary  strata 
are  broken  or  agitated,  but  proofs  are  not  wanting 
of  lesser  vibrations,  being  stopped  by  their  pressure. 
Hurnboldt  says,  he  has  seen  workmen  hasten  from 
the  mines  of  Mar  ien  burg  in  Saxony,  alarmed  by 
agitations  of  the  earth  that  were  not  felt  at  the  sur- 
face. During  the  earthquake  of  Lisbon,  the  miners 
in  Derbyshire  felt  the  rocks  muve  and, heard  noises 
which  were  scarcely  perceived  by  those  above. 

That  an  expansive  force  acting  from  beneath  is 
the  proximate  cause  of  earthquakes,  can  scarcely 
be  denied ;  and  the  prodigious  power  of  steam,  when 
suddenly  generated,  seems  equal  to  their  production, 
if  the  quantity  be  sufficiently  great.  The  great 
power  of  steam  at  high  temperatures  is  well  known, 


In  violent  earthquakes,  are  the  strata  ever  broken  ?  Afe 
shocks  ever  perceived  below  the  surface  that  are  not  felt  by 
those  on  the  surface  ?  What  is  supposed  to  produce  earth- 
quakes ? 


178  EARTHQUAKES,  &C. 

and  there  can  be  no  difficulty  in  admitting,  that,  if 
a  current  of  subterranean  water  were  to  find  access 
to  a  mass  of  lava  many  miles  in  extent,  and  most  in- 
tensely  heated,  it  would  produce  an  earthquake  more 
or  less  violent,  in  proportion  to  the  quantity  of  steam 
generated,  and  its  distance  from  the  surface." 

Coal  mines  are  sometimes  blown  up  in  conse- 
quence of  the  mixture  of  carbureted  hydrogen  gas 
and  air,  coming  in  contact  with  the  miner's  lamp. 
Hundreds  of  lives  are  thus  sometimes  destroyed  by 
a  single  explosion,  the  mine  becoming  an  immense 
piece  of  artillery,  and  every  object  in  and  near  the 
shaft  is  thrown  out  with  prodigious  violence.  The 
force  of  the  explosion  is  so  great  as  to  shake  the 
ground  like  an  earthquake  for  miles  around. 

The  Drainer  will  always  feel  grateful  to  Sir  Hum- 
phrey Davy,  the  inventor  of  the  safety  lamp.  This 
is  a  lamp  covered  by  a  frame  of  wire  gauze,  through 
which  the  flame  cannot  communicate,  so  as  to  ex- 
plode the  gas  on  its  exterior.  The  miner  can  now 
penetrate  a  work  in  the  mine,  where,  before,  it  would 
have  been  certain  death  to  approach. 

"  The  horrid  crash,  like  the  rattling  of  carriages, 
which  precedes  earthquakes,  may  be  occasioned  by 
the  rending  of  the  rocks,  or  parting  of  the  strata, 
through  which  the  confined  vapour  is  working  a 
passage." 

That  the  rising  and  falling  of  the  earth  during 


What  effects  are  produced  by  the  explosion  of  coal  mines  ? 
Who  was  the  inventor  of  the  safety  lamp  ?  What  is  the 
safety  lamp  ?  What  is  its  use  ?  What  causes  the  crackling, 
rumbling  noise  before  earthquakes  ?  What  evidence  have  we 
that  the  earth  actually  rises  and  falls  during  an  earthquake  ? 


EARTHQUAKES,  &C.  179 

earthquakes  is  not  imaginary,  is  demonstrated  by 
the  facts  observed  on  the  sea  shore.  The  water  is 
often  seen  to  recede  far  from  the  shore  and  then  re- 
turn  with  redoubled  violence.  The  effect  is  pro- 
duced by  the  rising  of  the  earth,  which  causes  the 
waters  to  flow  off,  and  on  its  sinking  again,  they 
return  in  high,  ridgy,  overwhelming  waves.  When 
Lisbon  was  destroyed,  the  return  wave  was  fifty  feet 
in  height. 

Volcanos  are  openings  made  in  the  earth's  sur- 
face by  internal  fires,  and  they  may  be  considered 
as  so  many  safety  valves,  of  the  districts  in  which 
they  are  found.  They  regularly,  or  at  intervals, 
throw  out  smoke,  vapour,  flame,  large  stones,  sand, 
and  melted  stone  called  lava.  Some  volcanos  throw 
out  torrents  of  mud  and  boiling  water.  • 

Volcanos  most  frequently  exist  in  the  vicinity  of 
the  sea  or  large  lakes,  and  also  break  out  from  un- 
fathomable depths  below  the  surface,  and  form  new 
islands  and  reefs  of  rock.  Humboklt  remarks  that 
all  the  ancient,  as  well  as  recent  volcanic  vents  of 
the  Andes,  have  opened  in  the  midst  of  trap,por- 
phyritic,  and  trachytic  rocks.  [Humboldt  on 
Rocks,  p.  33.] 

When  a  volcano  breaks  out  in  a  new  situation,  it 
is  preceded  by  violent  earthquakes,  the  heated  sur- 
face of  the  ground  frequently  swells  and  heaves  up, 
until  a  fissure  or  rent  is  formed,  sometimes  of  vast 
extent.  Through  this  opening,  masses  of  rock,  with 


What  are  volcanos  ?  What  do  they  eject  ?  How  are  most 
volcanos  located  in  relation  to  the  sea  ?  By  what  is  volcanic 
action  preceded  ? 


180  EARTHQUAKES,  &C. 

flame,  smoke  and  lava,  are  thrown  out  and  choke 
up  part  of  the  passage  and  confine  the  eruption  to 
one  or  more  apertures,  round  which  conical  hills  or 
mountains  are  formed. 

The  cause  of  the  conical  form  so  common  to 
volcanic  mountains  must  be  obvious  to  all,  who  are 
acquainted  with  the  circumstances  attending  an 
eruption.  The  ejected  matter  falling,  accumulates 
around  the  opening  in  a  circular  bank,  which  con- 
tinues to  increase  by  the  fresh  addition  of  materials, 
until  finally  it  forms  a  hill  or  mountain,  with  a  deep 
cavity  in  its  centre. 

The  concavity  in  the  centre  is  called  the  crater 
and  is  shaped  like  a  bowl  or  funnel,  shelving  steeply 
down  from  the  edge  to  the  bottom. 

Immense  volumes  of  aqueous  vapours,  are  evolv- 
ed from  a  crater  during  an  eruption,  and  even  for  a 
long  time  after  the  discharge  of  the  lava  and  sco- 
rise,  have  ceased. 

These  vapours  are  condensed  in  the  cool  atmos- 
phere, and  heavy  rains  are  produced  in  conse- 
quence. The  lightning  darts  amidst  the  clouds  of 
smoke,  and  the  thunder  peals,  as  if  in  mockery  of 
the  louder  thunders  of  the  volcano. 

The  heavy  rains  falling  on  a  surface  thick  cover- 
ed with  the  fine  ashes  and  loose  scoriae,  sweep  them 
along  in  a  flood  of  mud,  which  frequently  does  far 
more  mischief  than  the  lava  or  the  earthquakes. 


Explain  the  cause  of  the  conical  form  of  volcanic  moun- 
tains? What  is  the  crater  of  a  volcano?  What  vapours 
are  most  abundantly  evolved  from  volcanos  ?  What  effects 
are  produced  by  the  rapid  condensation  of  these  vapours  ? 


EARTHQUAKES,  &C.  181 

In  1822  one  of  these  mud  streams  descended  from 
Mount  Vesuvius,  and  after  destroying  much  culti- 
vated ground,  it  flowed  into  the  streets  of  St.  Sebas- 
tian, and  Massa,  where  it  filled  several  streets,  and 
some  houses,  and  destroyed  the  lives  of  seven  per- 
sons. [Comstock's  GeoL  p.  94.] 

This  mud  frequently  concretes  into  a  light  kind 
of  rock  which  is  much  used  in  building  wide  arch- 
es, on  account  of  its  lightness  and  strength.  The 
volcanos  in  the  Andes  are  said  to  throw  out  water 
and  rnud  more  frequently  than  lava.  The  deluge 
of  water  does  not  always  come  from  the  interior  of 
the  earth,  but  sometimes  from  the  snow  on  the  sum- 
mit of  the  mountain  being  rapidly  dissolved. 

Interior  cavities  of  vast  extent  and  depth  are 
sometimes  opened  during  an  eruption,  and  the  wa- 
ter with  which  they  were  filled  coming  in  contact 
with  ignited  lava  is  forcibly  driven  out ;  and,  ac- 
cording to  Humboldt,  carries  along  with  it  a  large 
quantity  of  small  fishes. — These  fishes  are  of  the 
same  species  that  inhabit  the  neighbouring  brooks 
and  lakes  :  the  number  thrown  out  is  often  so  great 
that  their  putrefaction  contaminates  the  air,  and 
occasions  serious  maladies  among  the  inhabitants 
of  the  adjacent  country.  . 

The  muddy  eruptions  of  the  Andes  cover  large 
tracts  of  country  with  a  bituminous  inflammable 
material,  which  is  used  by  the  inhabitants  for  fuel. 
It  is  called  moya. 


Do  volcanos  ever  throw  out  mud  and  water  ?     Does  the 
water  ever  contain  fishes?     Are  they  similar  to  those  of  the 
adjacent  lakes  ?     What  is  moya  ? 
16 


182  EARTHQUAKES,  &C. 

Boiling  and  hot  springs  must  be  classed  with  vol- 
canic phenomena.  They  are  most  common  in  vol- 
canic districts.  The  Geysers  of  Iceland,  which 
throw  up  hot  water  to  a  considerable  height  in  the 
air,  are  well  known. 

Hot  springs  are  common  in  some  parts  of  Europe, 
and  in  some  places  the  heat  is  applied  to  various 
economical  purposes,  as  for  warming  houses,  hatch- 
ing eggs,  &c. 

Hot  springs  have  been  observed  in  several  places 
in  the  United  States.  In  Arkansas,  on  the  Washita 
river,  a  considerable  number  of  these  springs  break 
out  from  the  side  of  a  hill,  and  in  a  ravine  between 
two  hills.  They  are  about  70  in  number,  and  vary 
in  their  temperature  from  90  to  140  degrees,  Fah- 
renheit's thermometer. 

"The  indications  ol  an  approaching  eruption 
fro-m  a  dormant  volcano,  are,  an  increase  of  smoke 
from  the  summit,  which  sometimes  rises  to  a  vast 
height  branching  in  the  form  of  a  pine  tree. — Tre- 
mendous explosions,  like  the  firing  of  artillery,  com- 
mence after  the  increase  of  smoke,  and  are  succeed- 
ed by  red  coloured  flames*  and  showers  of  stones. 
At  length,  the  lava  flows  out  from  the  top  of  the 
crater,  or  breaks  out  from  fissures  in  the  sides  of 


Are  boiling  springs  classed  with  volcanic  phenomena  ?  Is 
the  heat  of  hot  springs  ever  employed  for  useful  purposes  ? 
Have  hot  springs  been  observed  in  the  United  States  ?  Where 
have  several  been  found  ?  What  are  the  indications  of  an  ap- 
proaching eruption  from  a  dormant  volcano  ? 

*  The  flame  of  volcanos,  as  it  has  been  called,  is  found  to  be  the  RE- 
FLECTION or  LIGHT  from  the  lava  and  heated  materials,  gn  ttye  clouds 
of  dust  and  vapors  evolved  during  the  eruption, 


EARTHQUAKES,  &C.  183 

the  mountain,  and  covers  the  neighbouring  plains 
with  melted  matter,  which,  becoming  Consolidated, 
forms  a  stony  mass,  often  not  less  than  some  hun- 
dred square  miles  in  extent,  and  several  yards  in 
thickness. 

The  eruption  of  lava  has  been  known  to  continue 
several  months.  Intensely  black  clouds,  composed 
of  a  kind  of  dark  coloured  sand  or  powder,  impro- 
perly called  ashes,  are  thrown  out  of  the  crater  after 
the  lava  ceases  to  flow,  and  sometimes  involve  the 
surrounding  country  in  total  darkness  at  noonday. 
Towards  the  conclusion,  the  colour  of  the  volcanic 
sand  changes  to  white  :  it  consists  of  pumice  in  a 
finely  comminuted  state."  During  an  eruption  of 
jEtna,  a  space  of  150  miles  in  circuit  was  covered 
with  a  layer  of  volcanic  sand  12  feet  deep. 

"  When  the  lava  flows  freely,  the  earthquakes  and 
explosions  become  less  violent ;  which  proves  that 
they  were  occasioned  by  the  confinement  of  the 
erupted  matter,  both  gaseous  and  solid.  The  smoke 
and  vapour  of  volcanos  are  highly  electrical.  The 
quantity  of  lava  thrown  out  during  a  single  erup- 
tion of  a  volcano,  seems  almost  incredible  to  those 
who  have  not  observed  volcanic  countries.  Kircher, 
in  1660,  says,  the  ejections  of  Mount  ./Etna  would,* 
if  collected,  form  a  mass  twenty  times  as  large  as 
the  mountain  itself ;  and  a  few  years  afterwards, 
viz.  in  1669,  the  same  mountain  covered  with  a 
fresh  current  of  lava  84  square  miles ;  and  again, 
in  1775,  according  to  Dolomieu,  the  same  volcano 


What  are  the  appearances  and  effects  of  an  eruption  ?     Is 
the  quantity  of  ejected  matter  ever  very  great  ? 


184  EARTHQUAKES,  &C. 

poured  out  another  stream  oflava  12  miles  in  length, 
l\  in  hreath,  and  200  feet  deep." 

Hence  it  is  evident,  that  the  seat  of  the  fire  is  not 
in  the  mountain  itself,  but  deep  in  the  earth  *:  the 
volcano  is  not  the  furnace,  hut  the  chimney  ;  and 
it  will  be  necessary  to  bear  this  in  mind,  if  we 
would  form  an  adequate  idea  of  the  extensive  effects 
of  volcanic  action.  During  the  eruption  of  Skapta 
Jokul  in  Iceland,  in  1783,  two  immense  lava  cur- 
rents were  discharged,  one  40,  the  other  50  miles  in 
length,  averaging  11  miles  in  breath,  and  50  feet  in 
thickness. 

"The  most  extraordinary  volcanic  eruption  re- 
corded in  history,  for  the  extent  of  its  effects,  took 
place  in  Sumbawa,  one  of  the  Molucca  Islands,  in 
April,  1815.  This  eruption  extended  perceptible 
evidences  of  its  existence  over  the  whole  of  the 
Molucca  Islands,  over  Java,  a  considerable  portion 
of  Celebes,  Sumatra  and  Borneo,  to  a  circumference 
of  a  thousand  statute  miles  from  its  centre,  by  tre- 
mulous motions  and  the  report  of  explosions  ;  while 
within  the  range  of  its  more  immediate  activity, 
embracing  a  space  of  300  miles  around,  it  produced 
the  most  astonishing  effects,  and  excited  the  most 
alarming  apprehensions. 

In  Java,  at  the  distance  of  300  miles,  it  seemed 
to  be  awfully  present.  The  sky  was  overcast  at 
noonday  with  clouds  of  ashes  ;  the  sun  was  envelop- 
ed in  an  atmosphere,  whose  palpable  density  he  was 
unable  to  penetrate  ;  showers  of  ashes  covered  the 


Is  the  volcanic  mountain  the  seat  of  volcanic  fire  ?     Are 
the  explosions  of  volcanos  heard  at  great  distances  1 


EARTHQUAKES,  &C.  185 

houses,  the  streets  and  the  fields,  to  the  depth  of 
several  inches ;  and  amid  this  darkness,  explosions 
were  heard  at  intervals  like  the  report  of  artillery, 
or  the  noise  of  distant  thunder. 

So  fully  did  the  resemblance  of  the  noises  to  the 
report  of  cannon  impress  the  minds  of  some  officers, 
that  from  an  apprehension  of  pirates  on  the  coast, 
vessels  were  despatched  to  afford  relief.  Supersti- 
tion, on  the  other  hand,  was  busy  at  work  on  the 
minds  of  the  natives,  and  attributed  the  reports  to 
an  artillery  of  a  different  description  to  that  of  pi- 
rates.  All  conceived  that  the  effects  experienced 
might  be  caused  by  eruptions  of  some  of  the  numer- 
ous volcanos  on  the  Island ;  but  no  one  could  have 
conjectured  that  the  showers  of  ashes  which  dark- 
ened  and  covered  the  ground  of  the  eastern  districts 
of  Java,  could  have  proceeded  from  a  mountain 
in  Sumbavva,  at  the  distance  of  several  hundred 
miles." 

From  Sumbawa  to  the  part  of  Java  where  the 
sound  was  noticed,  is  970  geographical  miles.  The 
greatest  distance  to  which  the  eruption  of  a  volcano 
had  been  previously  heard,  is  600  miles ;  the  explo- 
sions of  Cotopaxi  are  sometimes  sensibly  heard  at 
that  distance  from  the  volcano,  which  is  one  of  the 
largest  and  highest  on  the  American  continent. 

Crater  of  Vesuvius  after  the  eruption  of  1822. 
The  vast  crater  which  was  emptied  by  the  violent 
action  of  the  volcano,  "  presents  an  aspect  very  dif- 
ferent from  that  which  is  usually  assumed  by  the 

Describe  the  appearance  of  the  crater  of  Vesuvius  after  the 
eruption  of  1822  ? 

16* 


186  EARTHQUAKES,  &C. 

concavities  of  volcanic  cones.  These  generally  ap- 
pear in  the  regular  form  of  an  inverted  cone,  whose 
sides  slope  at  about  the  same  angle  to  the  horizon, 
as  those  of  the  outer  cone.  This  is,  indeed,  invari- 
ably the  case,  with  every  cone  which  is  produced 
by  a  single  volcanic  eruption.  — 

"  That  of  Vesuvius,  however,  resulting  from  the 
accumulated  products  of  perhaps  many  hundred 
eruptions,  must  consist  of  numerous  beds  of  scoriae, 
and  fragmentary  lava,  alternating  with  strata  of 
lava  rock,  which  at  intervals  have  been  poured  in 
fiery  torrents  down  its  outer  slope  ;  and  congealing 
there,  have  remained  like  so  many  massive  ribs  to 
give  strength  and  solidity  to  the  structure. 

"  Through  this  succession  of  beds,  then,  has  the 
present  crater  been  forcibly  hollowed  out  by  the  ex- 
plosive energy  of  the  volcano.  It  appears  as  a  tre- 
mendous abyss  of  enormous  proportions,  surround- 
ed by  craggy  precipices,  that  rise  almost  vertically 
from  the  rude  heaps  of  fallen  fragments  which  form 
its  floor,  and  conceal  the  volcanic  orifice.  The  ex- 
treme periphery  of  the  crater  in  some  places,  juts 
over  these  precipices,  so  that  on  attaining  its  mar- 
gin you  look  directly  down  into  the  gaping  cavity.'' 

The  cliffs  that  encircle  the  great  cavity,  by  no 
means  follow  any  regularity  of  curve,  but  project  or 
recede  in  saleint,  and  retiring  angles.  Their  abrupt 
faces  which  are  rocky,  jagged,  and  unpicturesque 
in  the  extreme,  present  sections  of  many  currents 
of  lava,  some  of  which  are  of  great  thickness  and 


In  what  respect  does  this  differ  from  every  other  crater  that 
is  produced  by  a  single  eruption  ? 


EARTHQUAKES,  &C.  187 

extent,  lying  one  above  the  other  in  a  direction  more 
or  less  approaching  to  the  horizontal.  Most  of  them 
offer  a  columnar  division,  of  the  most  marked  and 
decisive  kind.  Some  are  almost  as  regularly  pris- 
matic as  any  ranges  of  the  older  basalts.  In  some, 
the  spheroidal  concretionary  structure  on  a  large 
scale,  is  equally  conspicuous.  Between  the  currents 
of  lava  are  interposed  shapeless  beds  of  volcanic 
conglomerate,  consisting  of  fragments  of  all  sizes, 
heaped  together  in  chaotic  confusion.  These,  as 
well  as  the  beds  of  lava,  are  occasionally  intersected 
by  vertical,  or  nearly  vertical  dykes,  similar  to  those 
of^Etna,  Monte  Sonuma,  dec. 

In  1828,  a  shock  of  an  earthquake  was  felt  at  the 
island  of  Pantellaria,  a  volcanic  island,  56  miles 
from  Sicily,  and  36  from  Africa ;  and  at  the  same 
time  a  violent  blast  of  hot  suffocating  air,  blew  off 
from  the  island  for  15  minutes.  At  Naples,  a  simi- 
lar sudden,  transient  gust,  of  hot  wind,  rushed  down 
the  bay  of  Naples,  towards  Castellamare,  proceeding 
to  a  different  point  of  compass  the  same  evening ;  and 
Vesuvius  which  had  been  for  some  time  slightly 
agitated,  threw  up  a  jet  of  flame,  and  smoke,  and 
then  resumed  its  former  state  of  partial  tranquillity. 
The  shock  of  an  earthquake  was  at  the  same  time 
felt  at  Ischia.  [Reports  of  British  As.  1832,  p. 
586.] 

"The  long  period  of  repose  which  sometimes  takes 
place  between  two  eruptions  of  the  same  volcano, 
is  particularly  remarkable.  From  the  building  of 


Do  volcanos  act  simultaneously  ?     Do  volcanos  ever  re- 
main  dormant  for  any  great  length  of  time  ? 


188  EARTHQUAKES,  &C. 

Rome  to  the  79th  year  of  the  Christian  era,  no  men- 
tion  is  made  of  Vesuvius,  though  it  had  evidently 
been  in  a  prior  state  of  activity,  as  Horculaneum 
and  Pompeii,  which  were  destroyed  by  the  eruption 
of  that  year,  are  paved  with  lava. 

"From  the  12th  to  the  16th  century  it  remained 
quiet  for  nearly  400  years,  and  the  crater  was  over- 
grown with  lofty  trees.  The  crater  was  descended 
by  Bracchini,  an  Italian  writer,  prior  to  the  great 
eruption  of  1631 :  the  bottom  was  at  that  time  a 
vast  plain,  surrounded  with  caverns  and  grottos. 
jEtna  has  continued  burning  since  the  time  of  the 
poet  Pindar,  with  occasional  intervals  of  repose, 
seldom  exceeding  30  or  40  years. 

"  Submarine  volcanos  are  preceded  by  a  violent 
boiling  and  agitation  of  the  water,  and  by  the  dis- 
charge of  volumes  of  gas  and  vapour,  which  take 
fire  and  roll  in  sheets  of  flame  over  the  surface  of 
the  waves.  Masses  of  rock  are  darted  through  the 
water  with  great  violence,  and  accumulate  till  they 
form  new  islands.  Sometimes  the  crater  of  the 
volcano  rises  out  of  the  sea  during  an  eruption. 

"  In  1783,  a  submarine  volcano  broke  out  near  Ice- 
land, which  formed  a  new  island  :  it  raged  for  seve- 
ral months  with  great  fury,  and  then  sunk  and  dis- 
appeared. Immediately  after  the  volcanic  island 
ceased  its  action,  the  great  eruption <of  Skapta  Jokul 
commenced  200  miles  distant.  In  1811,  a  small 
island  was  formed  by  a  submarine  volcano  at  a  little 
distance  from  St.  Michael's,  one  of  the  Azores."  It 


By  what  are  submarine  volcanos  preceded?    Are  vol- 
canic islands  often  raised  from  the  sea  ? 


EARTHQUAKES,  &C.  189 

has  now  sank,  and  has  500  feet  of  water  over  it. 
In  1831,  a  small  volcanic  island  appeared  in  the 
Mediterranean  Sea,  exhibiting  various  volcanic  phe- 
nomena, but  it  has  since  disappeared,  leaving  a 
shoal  in  its  place.*  The  appearance  of  new  vol- 
canic islands  above  the  ocean  is  not  of  rare  occur- 
rence :  very  many  such  events  are  recorded  in  his- 
tory. 

Among  the  volcanic  islands  which  have  disap- 
peared in  whole  or  in  part,  the  most  remarkable  is 
that  which,  in  1719  was  raised  near  Tercera.  In 
Nov.  1720,  it  was  visible  to  a  distance  of  7  or  8 
leagues,  and  was  3  leagues  in  diameter.  In  1723 
it  disappeared,  and  sunk  to  the  depth  of  nearly  500 
feet.  [Brongniart  Ter.  p.  198.] 

Sabrina,  which  was  elevated  near ,  the  Azores, 
disappeared  in  a  short  time ;  but  this  was  perhaps 
rather  owing  to  the  nature  of  the  materials  forming 
it,  than  to  the  sinking  of  the  island.  It  was  com- 
posed of  loose  cinders. 

The  rocks  near  Santorini  were  said,  in  (1836)  to 
be  rapidly  rising,  so  than  an  island  is  likely  soon 
to  appear. 

"  If  the  sea,  or  large  lakes,  have  once  covered  our 
continents,  it  follows,  that  the  greater  part  of  the 
present  and  ancient  volcanos  were  once  submarine.*" 


Name  some  instances  in  proof  of  their  appearance  and  dis. 
appearance  ?  Do  any  of  the  volcanos  on  the  land  appear  to 
have  been  once  submarine  ? 

*  The  shoal  has  now,  in  1833,  disappeared,  and  there  is  a  consider- 
able depth  of  water  where  the  shoal  was. 


190  EARTHQUAKES,  &C. 

Many  facts  indicate  that  JEtna  was  once  a  subma- 
rine volcano. 

"  Volcanos  frequently  occur  in  groups,  sometimes 
arranged  along  a  line  as  if  they  had  originally  been 
formed  over  one  vast  chasm.  The  volcanos  in 
South  America,  Hurnboldt  observes,  instead  of  being 
isolated  or  dispersed  in  irregular  groups,  as  in 
Europe,  are  arranged  in  rows,  like  the  extinct  vol- 
canos of  Auvergne,  or  the  volcanos  of  Java ;  some- 
times in  one  line,  and  sometimes  in  two  parallel 
lines." 

There  are  instances  of  volcanos  having  been  en- 
tirely engulphed  in  the  chasms  beneath  them.  The 
volcano  of  the  Pic  in  the  Island  of  Timor,  one  of 
the  Moluccas,  is  known  to  have  served  as  a  prodigi- 
ous watch-light,  which  was  seen  at  sea  at  the  dis- 
tance of  300  miles.  In  the  year  1638,  the  moun- 
tain, during  a  violent  eruption,  entirely  disappeared, 
and  in  its  place  there  is  now  a  lake.  Many  of  the 
circular  lakes  in  the  south  of  Italy  are  supposed  to 
have  been  formed  by  the  sinking  down  of  volcanos. 

The  Papandayang  was  formerly  one  of  the  largest 
volcanos  on  the  Island  of  Java,  but  the  greatest  part 
of  it  was  swallowed  up  in  the  earth  after  a  short  but 
very  severe  combustion  in  1772.  The  account  of 
this  event  says  :  "  Near  midnight,  between  the  llth 
and  12th  of  August,  there  was  observed  about  the 
mountain  an  uncommonly  luminous  cloud,  by  which 
it  appeared  to  be  completely  enveloped.  The  in- 


Do  volcanos  occur  in  groups  ?  How  are  they  frequently 
arranged?  Have  volcanic  mountains  ever  sunk  into  the 
earth  under  them  ? 


EARTHQUAKES,  &C.  191 

habitants,  as  well  about  the  fort  as  on  the  declivities 
of  the  mountain,  alarmed  by  this  appearance,  betook 
themselves  to  flight,  but  before  they  could  all  save 
themselves  the  mountain  began  to  give  way,  and  the 
greatest  part  of  it  actually  fell  in  and  disappeared 
in  the  earth.  At  the  same  time  a  tremendous  noise 
was  heard,  resembling  the  discharge  of  the  heaviest 
cannon.  It  was  estimated  that  an  extent  of  ground 
of  the  mountain  itself,  and  its  immediate  environs, 
15  miles  long  and  full  6  broad,  was,  by  this  commo- 
tion, swallowed  up  in  the  bowels  of  the  earth,  and 
about  3000  people  perished." 

There  are  very  many  evidences  that  volcanic  ac- 
tion has  been  far  more  active  in  former  periods  of 
time  than  at  present.  "  The  craters  of  many  an- 
cient  volcanos  are  of  far  greater  extent  than  the 
present  ones.  Vesuvius  is  a  comparatively  small 
cone,  raised  within  the  crater  of  a  larger  volcano. 
The  cone  of  the  Peak  of  Teneriffe  stands  within  a 
volcanic  plain  containing  36  square  miles  of  sur- 
face, surrounded  by  perpendicular  precipices  and 
mountains,  which  were  the  border  of  the  ancient 
crater." 

All  these  craters,  according  to  M.  Humboldt,  are 
diminutive  apertures,  compared  with  the  immense 
chasms  through  which,  in  remote  ages,  subterra- 
nean fire  has  forced  a  passage  through  the  crust  of 
the  globe.  Many  of  the  ancient  volcanic  rocks 
have  not  flowed  in  currents  from  limited  apertures 


Do  volcanos  appear  to  have  been  more  active  in  former 
times  than  at  present  ?  Do  the  ancient  volcanic  rocks  ap- 
pear to  have  flowed  in  currents  as  at  present  ? 


192  EARTHQUAKES,  &C. 

like  modern  lavas.  "  The  volcanic  porphyries  on 
the  back  of  the  Cordilleras,"  says  M.  Humboldt, 
"  are  undoubtedly  of  igneous  origin  ;  but  the  mode 
of  their  formation  is  not  like  modern  laves.  The 
action  of  volcanic  fire  by  an  insolated  cone  or  crater 
of  a  modern  volcano,  differs  necessarily  from  the 
action  of  this  fire,  through  the  fractured  crust  of  the 
globe. 

The  only  hard  crystalline  rocks  forming  at  the 
present  day  are  volcanic  ;  and  if  we  trace  the  con- 
nexion that  exists  between  the  modern  and  ancient 
volcanic  rocks,  and  between  the  latter  and  the  rocks 
of  trap  and  porphyry,  among  the  ancient  rock  for- 
mations, we  shall  extend  the  dominion  of  fire  over 
a  large  part  of  the  globe. 

Volcanic  rocks  are  principally  composed  of  feld- 
spar and  augite,  very  minutely  intermixed,  and  they 
vary  in  their  appearance,  as  one  or  the  other  of  these 
minerals  predominates.  The  lavas  in  which  feld- 
spar abounds,  have  generally  a  whitish  or  grayish 
colour,  and  melt  into  a  white  glass  :  those  in  which 
augite  predominates  are  dark  coloured,  and  melt 
into  a  black  glass. 

Various  mineral  substances  are  found  imbedded 
in  volcanic  rocks  or  in  their  fissures,  as  ores  of  iron 
bitumen,  mica,  garnet  divine,  iron  pyrites,  &c. 
The  different  structures  of  lava,  as  vitreous,  com- 
pact, stony  *and  scoriaceous  or  spongy,  depend  on 
the  different  circumstances  attending  its  cooling. 


Of  what  are  volcanic  rocks  composed  ?  Are  many  miner- 
al  substances  found  in  volcanic  rocks  ?  Upon  what  circum- 
stances does  the  difference  in  the  structure  of  lava  depend  ? 


EARTHQUAKES,  &C.  193 

if  cooled  rapidly,  it  is  vitreous ;  if  slowly,  under 
pressure,  it  is  compact  or  stony,  and  the  surface  of 
lava  currents  is  generally  scoraceous  or  spongy. 

Pumice  is  a  whitish  fibrous  spongy  lava,  and  so 
light  as  to  swim  on  water.  Immense  quantities  of 
pumice  are  sometimes  thrown  up  by  submarine  vol- 
canos.  It  has  been  seen  floating  upon  the  sea  over 
a  space  of  300  miles,  at  a  great  distance  from  any 
known  volcanos  ;  and  hence  it  may  be  inferred,  that 
submarine  volcanos  sometimes  break  out  at  such 
vast  depths  under  the  ocean,  that  none  of  their  pro- 
ducts reach  the  surface,  except  such  as  are  lighter 
than  water. 

Another  product  of  volcanos  is  sulphur.  In  the 
craters  of  some  extinct  volcanos,  it  occurs  in  great 
abundance,  and  is  quarried  out  like  stone  from  a 
common  quarry.  The  solfa-tara,  near  Naples,  is 
an  example,  and  various  salts  are  made  in  them,  as 
alum,  sal-ammoniac,  &c. 

Trachyte  is  the  name  given  to  a  whitish  volcanic 
rock,  the  grains  being  sometimes  very  minute,  and 
has  then  a  glistening  lustre.  It  is  mostly  composed 
of  feldspar,  and  sometimes  becomes  porphyritic,  and 
sometimes  passes  into  clinkstone. 

The  volcanic,  trap,  and  primitive  rocks,  pass  into* 
each  other  by  almost  insensible  shades,  and  it  seems 
almost  impossible  to  conceive  that  the  same  cause 
which  has  produced  one,  has  not  also  produced  the 

Has  pumice  ever  been  found  floating  far  from  any  known 
volcanos  ?  What  do  you  infer  from  this  ?  Where  is  sulphur 
found  ?  What  is  trachyte  ?  Do  the  trap  and  volcanic  rocks 
pass  into  each  other  ?  And  do  these  graduate  into  the  primi- 
tive rocks  ?  What  consequences  seem  to  follow  ? 
17 


194  RECAPITULATION. 

other;  but  at  different  times  and  under  different 
circumstances. 


CHAPTER  XIV. 

RECAPITULATION    OF   THE    PRINCIPAL    FACTS    OP 

GEOLOGY,  AND  A  SLIGHT  DISCUSSION  OF 

SOME  THEORIES. 

1.  The  earth's  surface  is  composed  of  various 
layers  of  sand,  clay,  and  rock,  and  various  mix- 
tures  of  these. 

2.  Rock  is  found  at  a  depth  varying  at  different ! 
places,  but  after  the  solid  rock  is  once  reached,  it 
continues  as  far  as  the  power  of  man  has  enabled 
him  to  penetrate. 

3.  There  are  many  kinds  of  rock,  each  having 
its  peculiar  characters. 

4.  These  rocks  have  particular  positions  in  re- 
gard to  each  other,  so  that   when  several  occur 
together,  they  lie  one  over  the  other  in  a  certain 
order,  which  is  never  inverted. 

5.  Rocks  sometimes  alternate  with  each  other, 
and  then  they  are  repeated  in  the  same  order  in 
each  successive  series. 

6.  The  layers  of  rocks  are  not  always  level,  but 

Of  what  is  the  earth's  surface  composed  ?  Is  rock  always 
found  below  the  susface  ?  Are  there  many  kinds  of  rock  ? 
Have  they  particular  positions  in  regard  to  each  other  ?  Do 
they  ever  alternate  ?  Are  the  layers  always  level  ? 


RECAPITULATION.  195 

are  often  more  or  less  inclined,  and  often  they  are 
nearly  vertical. 

7.  The  layers  are  not  always  plane,  but  some- 
times present  a  curved  and  bent  form. 

8.  Horizontal  layers  of  rock  sometimes  rest  or 
lie  upon  those  that  are  inclined,  but  the  reverse  is 
not  observed. 

9.  The  strata  of  rock  often  present  the  appear- 
ance of  having  been  cracked  through  like  ice,  and 
the  fissures  filled  up  with  stony  matter,  by  which 
the  rocks  are  again  cemented  together. 

10.  Veins  containing  the  same  minerals,  gene- 
rally traverse  the  rocks  in  particular  districts  in  the 
same  direction. 

11.  Several  sets  of  veins  are  sometimes  observed 
in  the  same  rocks,  each  set  having  its  particular 
minerals,  and  by  their  intersections,  the  relative 
ages  of  each  may  be  determined. 

12.  In  the  vicinity  of  these  veins,  fissures,  faults, 
and  dykes,  the  rocky  masses  often  appear  to  have 
been  moved  from  their  original   position.     They 
seem  to  have  been  tilted  in  a  direction  different 
from  the  mass  with  which  they  have  been  connect- 
ed, or  to  have  slipped  down  to  a  lower  level. 

13.  The  stony  material  of  the  veins  and  dykes  is  * 


Are  they  always  plane  ?  Do  horizontal  layers  ever  rest 
upon  inclined  ones  ?  Is  the  reverse  observed  ?  Do  the 
strata  appear  to  have  been  cracked  through  and  cemented 
together  again  ?  Do  particular  veins  follow  particular  direc- 
tions ?  Is  more  than  one  set  of  veins  ever  observed  in  the 
!same  rock  ?  What  appearance  is  observed  near  veins,  faults, 
'dykes,  &c.  ?  Is  the  stony  material  of  veins  always  different 
from  the  rock  through  which  it  passes  ? 


196  RECAPITULATION. 

sometimes  of  the  same  kind  as  the  rock,  but  fre- 
quently it  is  different,  and  sometimes  is  composed 
of  metallic  ores. 

14.  There  are  two  great  classes  of  rocks  distinct 
from  each  other  in  their  characters.     One  is  com? 
posed  of  mineral  substances  more  or  less  crystal- 
line  in  their  texture,  and  never  contains  the  remains 
of  animals  or  plants  imbedded  in  its  mass  ;    the 
other  is  composed  of  fragments  and  comminuted 
parts  of  the  first,  of  sand,  gravel,  or  clay  aggregat- 
ed and  cemented  together,  containing  sometimes 
wood,  various  remains  of  animals  and  plants,  or  of 
limestone,  which  is  often  almost  entirely  composed 
of  shells  and  the  remains  of  various  marine  ani- 
mals. 

15.  The  rocks  containing  the  remains  of  animals 
and  plants,  always  lie  over  those  that  do  not  con- 
tain them. 

16.  There  are  many  rocks  containing  organic 
remains,  and  each  of  the  series  of  formations  of 
these  rocks,  is  characterized  by  certain  groups  of 
fossils,  as  well  as  by  its  mineralogical  characters. 

17.  The  fossils  imbedded  in  the  rocks  lying  low- 
est in  the  series,  are  almost  entirely  different  from 
any  now  known  to  exist  in  our  seas,  or  on  our  Isl- 
ands or  continents. 

18.  The  fossil  organic  remains  imbedded  in  the 


How  many  great  classes  of  rock  occur  1  How  are  they 
distinguished  from  each  other  1  What  is  the  position  of  the 
fossiliferous  rocks  with  regard  to  those  which  are  not  so  ? 
Do  many  of  the  rocks  contain  fossils  ?  and  how  are  they 
characterized  ?  How  do  the  fossils  in  the  lowest  rocks  con- 
taining them,  compare  with  those  now  existing  ? 


RECAPITULATION.  197 

rocks  which  lie  higher  in  the  series,  approximate 
more  towards  existing  species,  and  in  the  rocks  of 
more  recent  origin,  many  of  the  species  are  simi- 
lar, and  perhaps  identical,  to  species  known  to  be  in 
existence. 

19.  The  rocky  strata  generally  have  their  outcrop 
parallel  to  the  principal  mountain  range,  and  they 
slope  off  from  it  on  each  side. 

20.  Certain  minerals  are  almost  constantly  asso- 
ciated with  certain  other  minerals,  or  in  particular 
rocks,  so  that  if  some  of  them  be  found,  the  others 
may  probably  be  found  by  search. 

21.  Volcanic  agency  has  been  often  exerted  to 
raise  enormous  masses  of  minerals  and  rocks  from 
a  lower  to  a  higher  level,  sometimes  in  a  fluid  form 
as  lava,  and  sometimes  in  the  solid  state,  as  volcanic 
islands  and  mountains,  and  even  large  tracts  of 
country. 

22.  Many  parts  of  the  surface  of  our  planet, 
have  bee'n  repeatedly  deluged  by  eruptions  of  lava. 

23.  Volcanos  of  the  present  time  rarely  produce 
as  compact  lavas  as  formerly. 

24.  Volcanos  are  now  nearly  inactive,  in  com- 
parison  with  their  former  state. 

25.  The  temperature  from  the  surface  of  the 

How  is  it  in  the  more  recent  rocks  ?  What  is  the  general 
direction  of  the  outcrop  of  strata  ?  Are  certain  minerals  as- 
sociated with  each  other  ?  Has  volcanic  agency  ever  been 
exerted  to  raise  islands  and  mountains  ?  Do  any  parts  of  the 
earth  appear  to  have  been  repeatedly  deluged  with  lava? 
How  do  recent  lavas  compare  with  the  ancient  ones  ?  Are 
volcanos  as  active  as  they  were  formerly  ?  Is  the  tempera- 
ture of  the  earth  variable  near  its  surface  ? 
17* 


198  RECAPITULATION. 

earth  to  a  depth  of  from  20  to  60  feet,  is  variable 
from  the  effect  of  the  seasons  and  the  filtering  of 
spring  water,  but  below  that,  the  temperature  is  con- 
stant at  the  same  point. 

26.  The  temperature  of  the  earth  is  variable  at 
different  places  at  equal  depths,  but  it  constantly 
increases  in  intensity  as  we  descend  farther. 

27.  This  increase  of  temperature,  varies  from 
one  to  two  degrees  of  Fahrenheit's  thermometer, 
for  every  100  feet  in  depth. 

28.  The  surface  of  the  earth  shows  that  it  has 
been  subjected  to  the  action  of  powerful  currents 
of  water,  since  all  the  regular  rock  formations  were 
deposited. 

29.  In  the  deposits  from  this  inundation,  the  re- 
mains of  innumerable  animals,  nearly  similar  to 
those  now  existing,  were  entombed. 

30.  Local  deposits  are  now  forming  from  the 
action  of  rain,  streams,  currents,  winds,  and  ani- 
mals, tending  to  modify  and  alter  the  present  suv  • 
face  of  the  earth. 

These  are  some  of  the  principal  facts  upon  which 
geology  rests  as  a  science.  Geology  is  a  science 
of  facts,  and  has  no  necessar3r  connection  with  any 


To  what  depth  ?  From  what  causes  ?  Is  it  variable  at 
equal  depths  in  different  places  ?  At  the  same  point,  how 
does  the  temperature  compare  at  different  times  ?  As  you 
descend  further  into  the  earth,  how  do  the  temperatures  com. 
pare  ?  How  much  does  the  temperature  increase  ?  What 
does  the  surface  of  the  earth  show  ?  What  are  found  in  the 
deposits  of  this  inundation  ?  Are  local  deposits  now  form, 
ing  ?  From  what  causes  has  geology  any  necessary  connec- 
tion with  theory  ? 


RE  CAPITULATION.  1 99 

of  the  various  theories,  which  have  been  brought 
forward  at  different  times  to  account  for  the  forma- 
tionW  the  earth.  Those  theories  were  framed  by 
their  authors  after  having  observed  a  few  facts,  and 
then  giving  a  free  course  to  their  imaginations  to 
carry  them  to  their  results. 

Theories  are  useful  to  the  progress  of  any  sci- 
ence, by  condensing  facts,  and  by  producing  an  ac- 
cumulation of  them  "  for  the  purposes  of  support  or 
attack."  [Cleveland's  Mineralogy,  p.  719.] 

There  are  two  theories  that  agitated  the  scien- 
tific world  for  some  time,  and  which  ought  not  to  be 
passed  over  in  silence.  They  are  founded  on  facts 
which  are  not  to  be  misunderstood.  Geologists  do 
not  admit  either  of  them  to  the  exclusion  of  the 
other,  but  adopt  such  parts  of  each,  as  are  support- 
ed  by  established  facts  and  strong  probabilities. 

The  reader  has  seen  that  fire  and  water  are  the 
active  agents  in  producing  changes  on  the  earth's 
surface  at  present.  It  was  owing  to  a  difference  of 
opinion  among  geologists,  as  to  whether  caloric,  or 
water,  was  formerly  the  agent  causing  the  changes 
which  are  indicated  by  the  various  geological  phe- 
nomena, that  these  two  theories,  the  Huttonian  and 
Wernerian,  were  formed.  They  are  also  frequent* 
ly  called  the  Vulcanian  and  Neptunian  theories. 

Before  proceeding  to  the  theories  themselves,  it 


Of  what  use  are  theories  ?  Have  any  particular  theories 
excited  much  discussion  ?  Are  they  founded  on  facts  ?  Do 
geologists  admit  either  of  them  fully  ?  What  parts  of  them 
are  admitted  ?  What  causes  are  now  effecting  changes  upon 
the  earth's  surface  ?  What  gave  rise  to  the  two  theories  re- 
ferred to  ?  What  are  they  called  ? 


200  WERNERIAN  THEORY. 

may  be  well  to  mention  some  points  upon  which 
they  depend,  and  which  are  supported  by  the  strong, 
est  evidence. 

1.  "  The  minerals,  which  compose  the  external 
crust  of  the  globe,  from  the  summit  of  the  highest 
mountain  to  the  lowest  point  hitherto  explored,  must, 
at  some  former  period,  have  been  in  a  fluid  state  ; 
and  the  solvent,  must,  unquestionably,  have  been 
caloric,  or  water." 

2.  "  The  distinctly  crystalline  structure  of  most 
of  the  primitive  rocks,  and  the  numerous  regular 
crystals   which  they  contain,  decidedly  indicate  a 
previous  state  of  fluidity." 

3.  "  The  numerous  organic  remains,  which  exist 
in  secondary  rocks,  unquestionably  prove,  that  such 
rocks  have  been  deposited  from  water.     It  is  well 
known,  that  different  sorts  of  secondary  rocks  have 
been  deposited  at  different  periods.    And  it  is  equal- 
ly  evident,  from  an  inspection  of  the  organic  re- 
mains in  secondary  rocks,  that  this  ancient  sea  was 
successively  peopled  by  different  races  of  animals." 
[Cleaveland.  722.] 

WERNERIAN  THEORY. 
«  At  some  former  period  this  globe  has,  for  a  long 


What  appears  to  have  been  the  state  of  the  materials  of  the 
earth  at  some  former  period  ?  What  is  the  structure  of  the 
primitive  rocks  ?  What  are  found  in  the  secondary  rocks  ? 
What  does  the  fact  prove  ?  Were  these  rocks  deposited  at 
different  periods  ?  Does  the  sea  appear  to  have  been  peo- 
pled by  different  races  in  succession  ?  What  is  the  Wer- 
nerian  theory  ? 


WERNERIAN  THEORY.  201 

time,  been  covered  with  water  to  a  greater  depth, 
than  the  original  altitude  of  the  highest  mountains. 
This  immense  body  of  water  ,was  then  tranquil,  or 
very  nearly  so,  and  contained  in  solution  all  the 
materials  of  which  the  present  crust  of  the  globe 
is  composed.  In  this  state,  chemical  deposits,  ex- 
hibiting more  or  less  of  a  crystalline  structure,  were 
gradually  made,  and  invested  the  nucleus  of  the 
globe. 

"  These  chemical  deposits  constitute  the  primitive 
rocks,  consisting  of  granite,  gneiss,  mica  slate, 
granular  limestone,  &c.  and  are  distinguished  by 
their  crystalline  structure,  and  by  the  total  absence 
of  organic  remains.  During  this  period,  most  of 
the  highest  mountains  were  formed  ;  for  their  sum- 
mits consist  of  primitive  rocks.  But,  by  a  gradual 
subsidence  of  the  waters,  the  summits  of  the  high- 
est  mountains  were  left  naked ;  the  tranquility  of 
the  waters  was  disturbed,  and  currents  were  conse- 
quently produced.  By  these  currents,  the  naked 
rocks  would  be  worn  and  partially  disintegrated ; 
and  the  grains  or  fragments  thus  produced,  would 
be  diffused  through  the  mass  of  water. 

"The  rocks  formed  at  this  period,  would,  of  course, 
consist  partly  of  chemical  and  partly  of  mechanical 
deposits.  They  would  also  lie  over  the  primitive 
rocks ;  but,  in  consequence  of  the  diminished  alti- 
tude of  the  waters,  they  would  appear  at  a  lower 
level,  often  resting  on  the  declivities  of  primitive 
mountains.  Many  of  the  rocks  of  this  period  con- 
tain organic  remains  of  marine  animals  and  marine 
plants. 

"  As  organic  remains  make  their  first  appearance 


202  WERNERIAN  THEORY. 

in  the  rocks  of  this  period,  it  is  supposed,  that  the 
rocky  shores,  which  had  recently  emerged  from  the 
great  deep,  were  passing  to  a  habitable  state.  Hence 
this  class  embraces  what  are  called  transition  rocks, 
consisting  of  graywacke,  some  varieties  of  lime- 
stone, greenstone,  argillite,"  &c. 

"  But  the  level  of  the  great  ocean  still  continuing 
to  sink,  more  extensive  portions  of  the  earth  were 
left  exposed  to  the  increasing  violence  of  the  cur- 
rents, and  the  solution  which  was  originally  chemi- 
cal, now  became  in  a  great  degree  composed  of 
grains  or  comminuted  fragments,  detached  from  the 
older  rocks. 

"  Hence  the  minerals  of  this  period  consist  chiefly 
of  mechanical  deposits.  They  lie  over  the  two  pre- 
ceding classes,  but  still  appear  at  a  lower  level,  in 
censequence  of  a  greater  subsidence  of  the  waters. 
Hence,  also,  they  are  found  near  the  base  of  high 
mountains,  or  in  hills  of  moderate  height,  or  in  val- 
lies,  or  under  plains,  sometimes  at  a  great  distance 
below  the  earth's  surface.  This  class  is  composed 
of  the  secondary  rocks,  and  embraces  sandstone, 
most  varieties  of  compact  limestone  and  of  gyp- 
sum, chalk,  basalt,  some  varieties  of  greenstone, 
coal,  &c. 

"  Extensive  portions  of  the  crust  of  the  globe  had 
now  become  dry :  new  species  and  genera  of  ani- 
mals inhabited  the  waters,  or  dwelt  on  the  land, 
while  numerous  vegetables  adorned  the  shores  and 
other  parts  of  the  earth's  surface.  Hence  the  se- 
condary rocks  abound  with  organic  remains,  both 
of  animals  and  vegetables.  Hence,  also,  the  abun. 


HUTTONIAN  THEORY.  203 

dance  of  bituminous  substances  in  this  class  hav- 
ing proceeeded  from  the  decay  of  organized  bodies. 

"  There  are  a  few  exceptions  to  the  general  fact 
concerning  the  low  level,  at  which  the  secondary 
rocks  usually  appear ;  for  they  sometimes  rest  on 
the  summits  of  mountains  highly  elevated.  Basalt 
and  wacke  are  among  the  secondary  rocks  thus 
found.  These  elevated  strata  of  secondary  rocks 
are  supposed  by  Werner  to  have  been  deposited 
during  a  second  and  sudden  rise  of  the  ocean,  after 
it  had  once  greatly  subsided. 

"  The  preceding  deposits  of  rocks  are  supposed  to 
have  been  universal  formations,  "  like  the  coats  of 
an  onion.  But  various  subsequent  revolutions  and 
changes,  have,  in  many  instances,  destroyed  or  con- 
cealed the  continuity  of  strata.  This  universality 
in  the  formations  of  rocks,  is  an  important  point  in 
this  system.  Two  other  classes  of  comparatively 
small  extent,  viz :  alluvial  deposits  and  volcanic 
ejections,  complete  the  series  of  mineral  forma- 
tions." [Cleaveland,  p.  723.] 

HUTTONIAN  THEORY. 

"  In  the  the  theory  of  Dr.  Hutton,  caloric  is  the 
most  important  agent.  This  theory  supposes  the 
solid  crust  of  the  present  globe,  to  have  proceeded 
from  the  disintegration  and  destruction  of  former 
continents  by  the  gradual  action  of  the  atmosphere 
and  water — that  the  ruins  of  those  ancient  conti- 
nents were  transported  by  water,  and  deposited  at 

Give  the  Huttonian  theory  ? 


204  RECAPITULATION. 

the  bottom  of  the  ancient  seas — and  that  these  he- 
terogeneous  materials,  thus  deposited,  were  consoli. 
dated  by  the  action  of  subterraneous  fire  :  and,  by 
the  same  agent,  were  subsequently  elevated  to  form 
the  present  continents. 

"It  further  supposes,  that  gneiss  and  other  stratifi- 
ed rocks,  were  only  softened,  elevated,  and  some- 
times variously  inclined,  while  granite  and  other 
unstratified  minerals,  were  completely  fused,  and, 
in  many  cases,  forced  upward  by  this  powerful 
agent  through  the  superincumbent  strata.  Hence 
we  find  granite  summits  surrounded  by  gneiss,  mica 
slate,  &c.  Hence,  also,  metallic  veins  were  filled 
from  below  by  injections  of  melted  matter. 

"  By  a  similar  process,  this  theory  provides  for  the 
disintegration  and  partial  destruction  of  existing 
mountains  and  continents,  and  for  their  transporta- 
tion to  the  bottom  of  present  oceans,  from  which,  b/ 
the  action  of  subterraneous  fire,  they  are  again  to 
be  raised  and  constitute  new  and  future  continents." 
[Cleavdand,  p.  726.] 

The  Wernerian  theory  is,  in  many  parts,  founded 
on  a  close  observation  of  facts ;  but  it  is  so  inter- 
woven with  hypothetical  points,  which  are  not  con- 
firmed  by  succeeding  observations  in  other  parts  of  * 
'  the  world,  that  it  cannot  be  received.  It  is  not  all 
true,  and  it  does  not  account  for  all  the  facts. 

The   Huttonian   theory   consists   of   inferences 
drawn  from  facts,  but   the  deductions   are  some- 
Is  the  Wernerian  theory  founded  on  facts  ?     Are  his  theo- 
retical conclusions  confirmed  ?     Are  the  deductions  of  the 
Huttonian  theory  carried  farther  than  facts  warrant  ? 


RECAPITULATION.  205 

times  carried  farther  than  the  facts  warrant.  It 
supposes  the  present  continents  derived  from  the 
wrecks  of  older  ones,  because  we  find  a  large  por- 
tion of  the  rocks  upon  the  surface  of  the  earth  form- 
ed of  the  fragments  of  others  cemented  together, 
and  often  filled  with  the  remains  of  animals  that 
once  inhabited  the  sea. 

But  whether  volcanic  agency  has  caused  those 
lands  to  be  elevated,  which  have  evidently  been  for 
a  long  period  under  the  surface  of  the  ocean,  is  a 
point  which  is  not  conceded  by  all.  It  is,  however, 
rendered  highly  probable  by  some  facts  which  have 
been  mentioned  under  the  head  of  volcanos  and 
earthquakes. 

The  Huttonian  theory  supposes  the  secondary 
rocks,  after  they  were  formed  in  the  bed  of  the 
ocean,  to  have  been  indurated  by  subterranean  heat, 
before  they  were  raised  to  become  islands  and  con- 
tinents. Some  experiments  by  Sir  James  Hall, 
which  have  been  already  mentioned,  render  this 
supposition  probable. 

The  Huttonian  theory  supposes  the  earth  to 
have  once  been  in  a  melted  state,  and  to  have  cool- 
ed gradually. 

The  phenomena  of  volcanos  and  veins,  and  the 
constantly  increasing  temperature  observed  in  pen- 
etrating below  the  surface,  seem  to  justify  the  con- 
clusion that  the  earth  has  been  fluid,  and  that  it 
still  may  be  so  at  a  considerable  depth  below  its 
surface. 


Are  his  deductions  rendered  highly  probable  ?     What  justi- 
fies the  conclusion  that  the  earth  has  been  in  a  melted  state  ? 
18 


206  RECAPITULATION. 

Since  the  discovery  by  Sir  Humphrey  Davy  that 
the  alkalies  and  earths  are  metallic  oxides,  some 
have  supposed  the  interior  of  the  earth  to  be  a  mass 
of  the  earthy  and  alkaline  metals.  Many  of  these 
metals  when  in  contact  with  water  decompose  it, 
and  burn  with  the  evolution  of  immense  heat.  Large 
quantities  of  gaseous  matter  and  vapour  are  pro- 
duced. 

If  the  waters  of  the  ocean  were  to  filter  through 
the  fissures  of  the  rocks  and  come  in  contact  with 
such  materials  as  many  suppose  to  constitute  the 
interior  of  the  earth,  intense  heat  would  be  evolved, 
the  materials  would  be  melted,  if  they  were  not  so 
already,  highly  elastic  vapours  and  gasses  would  be 
formed  in  immense  quantities,  and  all  the  phenom- 
ena of  volcanos  and  earthquakes  would  be  produc- 
ed. The  effects  would  account  for  most  of  the  facts 
observed,  as  in  metallic  and  other  veins,  dislocation, 
obliquity,  contortion  of  strata,  &c. 

In  concluding  this  sketch  of  geology,  it  may  not 
be  amiss  to  give  Prof.  Sillirnan's  views  of  volcanic 
phenomena,  and  they  are  also  applicable  to  the  ex- 
planation of  most  geological  facts.  His  views  are 
not  entirely  original,  but  have  been  extended  much 
beyond  the  suggestions  which  led  to  them. 

"  The  act  of  creative  energy,  admitted  alike  by 
religion  and  philosophy,  necessarily  implies  the  pro- 
duction of  all  the  elements  of  which  our  physical 
universe  is  composed.  How  far  these  elements 


Of  what  is  the  interior  of  the  earth  supposed  by  some  to  be 
mposed  ?     What  woul " 
>on  this  supposition  ? 
of  the  facts  of  geology  ? 


i  composed  ?     What  would  be  the  theory  of  volcanic  action 
I  upon  this  supposition  ?     Would  the  effects  account  for  most 


RECAPITULATION.  207 

were  originally  united  in  binary,  ternary,  or  still 
more  complex  combinations,  we  cannot  possibly 
know.  The  revelation  of  this  fact,  not  being  ne- 
cessary to  our  moral  direction,  has  been  withheld 
by  the  Creator,  and  we  know  only,  that,  '  In  the 
beginning,  God  created  the  heavens  and  the  earth.' 
As  to  the  actual  condition  of  the  elements,  at  that 
primeval  period,  science  may  fairly  inquire,  and  is 
justified  in  reasoning  within  the  limits  prescribed 
by  our  moral  condition  and  intellectual  powers. 

"  If  we  suppose  that  the  first  condition  of  the 
created  elements  of  our  planet,  was  in  a  state  of 
freedom  ;  the  globe  beihg  a  mass  of  uncombined 
combustibles  and  metals,  and  that  the  waters,  the 
atmosphere,  and  chlorine,  and  iodine,  and  perhaps 
hydrogen,  were  suddenly  added  ;  it  will  be  obvious, 
from  what  we  know  of  the  properties  of  these  ele- 
ments, that  the  reaction,  awakening  energies  before 
dormant,  would  produce  a  general  and  intense  igni- 
tion, and  a  combustion  of  the  whole  surface  of  the 
planet. 

"  Potassium,  sodium  and  phosphorus  would  first 
blaze,  and  would  immediately  communicate  the  heat 
necessary  to  bring  on  the  action  between  the  other 
metals  and  combustibles,  in  relation  to  the  oxygeft 
and  chlorine,  and  in  relation  to  each  other.  Thus 
a  general  conflagration  would  be  the  first  step  in 
chemical  action. 

"  In  this  manner  mi^ht  be  formed  the  fixed  alka- 


What  are  Prof.  Silliman's  views  upon  the  supposition  that 
the  interior  of  the  earth  is  composed  of  the  alkaline  and 
earthy  metals  ? 


208  RECAPITULATION. 

lies,  the  earths  and  stones  and  rocks, — the  metallic 
oxides  properly  so  called, — the  sulphurets  and  phos- 
phurets  of  the  metals,  —  carburet  of  iron, — the 
acids,  including  the  muriatic, — and  ultimately,  the 
salts,  and  chlorides,  alkaline,  earthy  and  metallic, 
and  many  other  compounds  resulting  either  from  a 
primary  or  secondary  action. 

"In  such  circumstances,  there  would  also  be 
great  commotion  :  steam,  vapours  and  gases  would 
be  suddenly  evolved  in  vast  quantities,  with  explosive 
violence ;  the  imponderable  agents,  heat,  light,  elec- 
tricity and  magnetism,  and  attraction,  in  various 
forms,  would  be  active  in  an  inconceivable  degree, 
and  the  recently  oxidized  crust  of  the  earth  would 
be  torn  with  violence,  producing  fissures  and  cav- 
erns, dislocations  and  contortions,  and  obliquity  of 
strata  ;  and  it  would  every  where  bear  marks  of  an 
energy  then  general,  but  now  only  local,  and  occa- 
sional. 

"  It  is  however  obvious,  that  this  intense  action 
would  set  bounds  to  itself;  and  that  the  chemical 
combinations  would  cease,  when  the  crust  of  in- 
combustible matter  thus  formed,  had  become  suffi- 
ciently thick  and  firm,  to  protect  the  metals  and 
combustibles  beneath,  from  the  water  and  air,  and 
other  active  agents. 

"  As  we  are  not  now  giving  a  theory  of  the  earth, 
but  merely  stating  the  conditions  of  a  problem,  we 
forbear  to  descant  upon  many  obvious  collateral 
topics,  or  to  pursue  the  primitive  rock  formations 
through  the  vicissitudes  which  might  have  attended 
them.  We  do  not  even  say,  that  we  believe  that 
such  events  as  we  have  attempted  to  describe,  did 


RECAPITULATION.  209 

actually  happen ;  we  say  only  that  their  existence 
is  consistent  with  the  known  properties  of  the  chem- 
ical elements,  and  with  the  physical  laws  of  our 
planet. 

"  Supposing  that  such  was  the  actual  state  of 
things,  it  is  obvious  that  the  oxidated  crust  of  the 
globe  would  still  cover  a  nucleus,  consisting  of  me- 
tallic and  inflammable  matter.  Of  course,  when- 
ever air  and  water,  or  saline  and  acid  fluids,  might 
chance  to  penetrate  to  this  internal  magazine,  the 
same  violent  action  which  we  have  already  suppos- 
ed to  have  happened  upon  the  surface,  would  recur, 
and  the  confinement  and  pressure  of  the  incumbent 
strata,  increasing  the  effects  a  thousand  fold,  would 
necessarily  produce  the  phenomena  of  earthquakes 
and  volcanos. 

"  Still,  it  is  equally  obvious,  that  every  recurrence 
of  such  events,  must  oxidize  the  earth  deeper  and 
deeper,  and  if  the  point  should  ever  be  attained,  when 
water  or  air  ceased  to  reach  the  inflammable  nu- 
cleus, or  the  nucleus  were  all  oxidized,  the  phenomena 
must  cease,  and  every  approximation  towards  this 
point  would  render  them  less  frequent. 

"  Does  this  correspond  with  the  actual  history  of 
these  events  ?  Are  they  now  less  frequent,  than  jn 
the  early  ages  of  our  planet  ?  The  extensive  re- 
gions occupied  by  rocks  of  acknowledged  igneous 
origin,  but  where  fire  is  not  now  active,  would  seem 
to  favour  this  idea  ;  but  the  answer  to  this  question 
must  depend  so  much  upon  the  theoretical  views  en- 
tertained of  the  formation  of  granite,  and  of  the  other 
primitive  rocks,  that  it  may  be  impossible,  at  present, 
to  bring  it  to  a  decision, 

18* 


210  RECAPITULATION. 

"  Whatever  we  may  think  of  the  hypothesis,  now 
detailed,  may  we  not  suppose,  with  sufficient  proba- 
bility, that  those  voltaic  powers  which  we  know  to 
exist — whose  action  we  can  command,  and  whose 
effects  having  been  first  observed  within  the  me- 
hiory  of  the  present  generation,  now  fills  us  with  as- 
tonishment — are  constantly  active  in  producing  the 
phenomena  of  earthquakes  and  volcanos  ? 

"  Arrangements  of  metals  and  fluids  are  the  com- 
mon means  by  which  we  evolve  this  wonderful 
power,  in  our  laboratories  ;  and  it  would  seem  that 
nothing  more  than  juxta-position,  in  a  certain  order, 
is  necessary  to  the  effect.  Even  substances  appa- 
rently dry  and  inert  with  respect  to  each  other,  will 
produce  a  permanent,  and,  in  proportion  to  the 
means  employed,  a  powerful  effect ;  as  in  the  col- 
umns of  De  Luc  and  Zamboni. 

"  It  would  seem  indeed  that  metals  and  fluids  are 
not  necessary  to  the  effect.  Arrangements  of  al- 
most any  substances  that  are  of  different  natures, 
will  cause  the  evolution  of  this  power.  Whoever 
has  witnessed  the  overwhelming  brilliancy  and  in- 
tense energy  of  the  great  galvanic  combinations, 
especially  of  the  deflagrator  of  Dr.  Hare,  and  con- 
siders how  very  trifling  in  extent  are  our  largest 
combinations  of  apparatus,  compared  with  those 
natural  arrangements  of  earths,  salts,  metals  and 
fluids,  which  we  know  to  exist  in  the  earth,  in  cir- 
cumstances similar  to  those,  which,  in  our  labora- 

What  is  said  of  the  effect  of  the  voltaic  powers  ?  .  Are 
such  phenomena  produced  by  the  different  rocky,  earthy  and 
fluid  materials  of  the  globe  ?  Would  the  theory  account  for 
most  of  the  observed  facts  of  geology  ? 


RECAPITULATION.  211 

lories,  are  effectual  in  causing  this  power  to  appear, 
will  not  be  slow  to  believe,  that  it  may  be  in  the 
earth  perpetually  evolved  and  perpetually  renewed; 
and  now  mitigated,  suppressed  or  revived,  accord- 
ing to  circumstances  influencing  the  particular  state 
of  things  at  particular  places. 

"  In  our  laboratories,  we  see  emanating  from  this 
source,  intense  light,  irresistible  heat,  magnetism  in 
great  energy,  and  above  all  a  decomposing  power, 
which  commands  equally  all  the  elements  and  prox- 
imate principles  in  all  their  combinations. 

"  Sir  Humphrey  Davy,  after  discovering  that  the 
supporters  of  combustion  and  the  acids,  were  all 
evolved  at  the  positive  pole,  and  the  combustibles 
and  metals,  and  their  oxidated  products,  at  the  ne- 
gative— proved,  that  even  the  firmest  rocks  and 
stones  could  not  resist  this  power,  their  immediate 
principles  and  elements  being  separated  by  its  en- 
ergy. 

"  The  decomposition  of  the  alkalies,  earths,  and 
other  metallic  oxides,  being  a  direct  and  now  fami- 
liar effect  of  voltaic  energy — their  metals  being  set 
at  liberty,  and  being  combustible  both  in  air  and 
water — elastic  agents  produced  by  this  power,  and 
rarified  by  heat,  being  also  attendant  on  these  de- 
compositions, it  would  seem  that  the  first  principles* 
are  fully  established  by  experiment,  and  that  no- 
thing is  hypothetical,  but  the  application  to  the  phe- 
nomena of  earthquakes  and  volcanos. 

"  It  appears  an  important  recommendation  of  the 
present  view,  that  causes  are  here  provided  which 
admit  of  indefinite  continuation,  and  of  unlimited 
renovation. — There  appears  no  reason  why,  on  the 


212  RECAPITULATION. 

whole,  the  phenomena  should  cease,  as  long  as  the 
earth  exists.  It  has  therefore  the  great  Newtonian 
requisites  of  a  good  theory  ;  its  principles  are  true, 
and  it  is  sufficient." — [Silliman's  outline  in  the  1st 
American  edition  of  BakeweWs  Geology,  pp.  115 — 
119.] 


USEFUL  APPLICATION  OF  GEOLOGY. 


I.  AGRICULTURE. 

Almost  every  farmer  is  practically  acquainted 
with  the  fact,  that  the  value  of  a  soil  is  dependent 
upon  the  nature  of  the  materials  of  which  it  is  form- 
ed, its  texture,  and  the  rocky,  or  earthy  substratum. 

Soils  are  commonly  divided  into  heavy  or  clayey 
soils;  light,  or  sandy,  loamy  or  warm  soils;  and 
cold  or  wet  soils ;  and  these  variations  are  due  to 
two  general  causes,  viz :  the  nature  of  the  materials 
forming  the  soil,  and  the  substratum. 

Soils  result  from  the  disintegration  and  decompo- 
sition of  the  subjacent  materials,  and  the  mixture 
of  this  earthy  matter  with  decomposed  vegetable 
substances  ;  with  the  excrements  of  animals  ;  with 
the  remains  of  insects  and  worms  which  once  in-* 
habited  the  surface ;  and  with  parts  of  quadrupeds 
and  birds  which  have  perished,  and  whose  remains 
have  not  been  altogether  removed  by  those  insects, 
birds,  and  animals,  which  prey  upon  putrid  animal 
matter. 

"  As  we  are  almost  exclusively  dependent  upon 
the  soil,  for  those  articles  of  food  and  raiment,  ne- 
cessary to  the  supply  of  our  animal  wants ;  and  as 


214  AGRICULTURE. 

the  annual  products  of  the  soil  form  the  largest  item 
in  the  increasing  wealth  of  the  country,  it  is  deemed 
expedient  to  consider  this  subject  with  some  atten- 
tion. 

All  the  richest  and  most  densely  populated  agri- 
cultural districts,  are  on  the  transition,  secondary, 
tertiary,  and  alluvial  formations.  Soils,  with  the 
exception  of  those  resulting  from  alluvial  depositions, 
are  derived  from  the  disintegration  and  decomposi- 
tion of  the  subjacent  materials,  and  they  depend  in 
a  great  degree,  for  their  qualities,  upon  their  me- 
chanical and  chemical  constitution ;  hence  the 
geology  of  a  territory  is  a  necessary  pre-requisite  in 
estimating  the  agricultural  characters  and  value  of 
its  soils. 

The  variations  in  the  productiveness  of  soils,  are 
due  to  two  general  causes, — viz  : 

1st.  The  mechanical  texture  of  the  soils. 
2d.  Their  chemical  composition. 

1st.  The  texture  of  a  soil  is  a  character  of  more 
importance  than  is  generally  supposed.  To  form  a 
good  soil,  its  texture  should  he  such  as  to  retain  a 
suitable  quantity  of  moisture  for  the  nourishment  of 
vegetation,  and  be  neither  so  clayey  as  to  bake  and 
crack  in  the  heat  of  the  sun,  or  heave  by  the  action 
of  frost ;  nor  so  sandy  as  to  become  parched,  and 
be  mere  dust  at  the  depth,  to  which  the  roots  of 
plants  penetrate.  Argillaceous  soils  have  so  strong 
an  affinity  for  water,  as  to  retain  a  small  portion 
even  when  heated.  There  should  be  a  sufficient 
quantity  of  clay  in  soils,  to  enable  them  to  retain  3 
or  4  per  cent  of  water  when  dry,  and  to  convert  the 


AGRICULTURE.  215 

other  materials  into  a  loam.     Perhaps  a  light  loam, 
properly  treated,  produces  the  best  crops. 

It  is  also  necessary  to  consider  the  substratum,  in 
judging  of  the  productiveness  of  any  particular  soil. 
If  it  be  clay,  or  rock  without  fissures,  the  soil,  how- 
ever good  in  its  texture  and  other  qualities,  will  pro- 
bably be  "cold  and  wet."  If  the  sub-soil  be  gravel 
or  sand,  the  surface  soil  is  frequently  too  dry,  unless 
it  be  a  loam  so  heavy,  as  to  retain  a  sufficient  quan- 
tity of  moisture  for  vegetation. 

When  a  clay  sub-soil  occurs,  it  often  alternates 
with  beds  of  gravel  and  sand.  Advantage  may  often 
be  taken  of  this  geological  fact  to  drain  wet  soils, 
either  by  boring,  or  sinking  wells  through  the  clay, 
into  the  gravel  or  sand  below,  so  that  the  water  will 
find  an  outlet  in  the  springs  at  a  lower  level,  where 
these  strata  emerge  on  the  sides  of  hills  or  ravines. 
In  this  way,  stagnant  ponds  and  marshes  may  be 
drained,  not  only  so  as  to  reclaim  unproductive 
lands,  but  to  render  the  surrounding  country  more 
healthful.  These  principles  may  be  practically  ap- 
plied in  many  parts  of  the  country. 

However  poor  the  texture  of  a  soil,  it  can  always 
be  brought  to  a  proper  state  of  cultivation  by  art ; 
but,  the  value  of  produce,  and  the  price  of  labour 
will  not  often  justify  the  expense.  Light  and  heavy 
soils  may  always  be  benefitted  by  a  proper  admixture 
of  clay  or  sand,  as  the  case  may  require.  That  clay 
and  sand  are  almost  always  associated,  is  a  geologi- 
cal fact  of  much  practical  value  in  agriculture,  as 
well  as  in  the  arts.  The  occurrence  of  one,  ('unless 
from  the  effect  of  some  local  cause,)  is  a  pretty  sure 
indication  that  the  other  may  be  found  in  the  vici- 


216  CHEMICAL  COMPOSITION  OF  SOILS. 

nity.  Light  dry  soils  are  often  injured  by  removing 
the  small  loose  stones,  which,  instead  of  being  an  in- 
jury, are  in  reality  an  advantage,  as  they  not  only 
prevent  the  evaporation  of  moisture  below  the  sur- 
face, by  shading  the  ground  ;  but,  by  their  slow  de- 
composition, furnish  stimulants  and  food  for  vegeta- 
tion, these  acting  as  a  permanent  manure. 

2d.  CHEMICAL  COMPOSITION  OF  SOILS. 

The  chemical  as  well  as  the  mechanical  composi- 
tion of  soils,  exerts  a  powerful  influence  on  vegeta- 
tion. Salts,  alkalies,  and  alkaline  earths,  act  as 
stimulants  if  used  moderately  ;  but  if  in  excess,  they 
are  injurious.  Many  soils  contain  calcareous  rocks, 
stones,  or  pebbles,  which  are  continually  undergoing 
disintegration  and  solution  by  atmospherical  agents ; 
and  thus  serve  as  permanent  mineral  manures. 
Other  soils  abound  in  stones  derived  from  such  rocks 
as  contain  potassa  as  a  constituent,  and  by  their 
decomposition,  furnish  this  alkali,  in  solution  to  the 
roots  of  plants,  by  which  it  is  absorbed  and  carried 
into  the  circulation,  and  there  acting  as  a  stimulant, 
remains  combined  with  some  vegetable  acid.  The 
decomposition  of  gravel,  pebbles  and  rock  has  been 
observed  to  be  a  benefit  to  vegetation ;  and  as  the 
rapidity  of  decomposition  depends  upon  the  surface 
exposed,  it  follows,  that  if  such  materials  be  ground 
fine  and  sowed  upon  the  soil,  like  plaster  of  paris, 
a  more  decided  benefit  would  be  the  result.  This 
has  been  partially  tried  with  success ;  and  it  is  to 
be  hoped  that  intelligent  farmers  will  give  it  a  more 
thorough  trial. 


PERMANENCY  OF  SOILS.  217 

Iron  in  some  states  of  combination,  exercises  a 
beneficial  influence  on  vegetation ;  yellowish  and 
reddish  soils  almost  always  contain  iron,  and  are 
generally  productive. "  [Mathers  Geological  Re- 
ports to  New  York  and  to  Ohio.] 

PERMANENCY  OF  SOILS. 

The  permanency  of  a  soil  is  dependent  upon  its 
tendency  to  wash,  and  its  vegetable  cover.  If  the 
soil  be  of  such  a  texture  as  to  wash  easily,  it  can- 
not be  permanent  on  steep  slopes  of  hills,  unless 
they  remain  constantly  covered  with  grass  sward, 
or  forests,  or  other  vegetable  growth,  the  fibrous 
rootlets  of  which,  bind  the  earth  together,  and  pre- 
vent its  removal. 

The  substratum  must  also  be  taken  into  conside- 
ration, in  judging  of  the  probable  permanency  of  a 
soil  which  it  is  proposed  to  till.  Many  soils  which 
shed  water  to  a  certain  extent  without  washing, 
when  covered  by  native  forests  or  grass  sward,  be- 
come so  porous  when  tilled,  as  to  absorb  much  water, 
and  if  the  substratum  be  clay  or  sloping  rock  which 
does  not  permit  the  water  to  permeate  it,  the  super, 
incumbent  soil  slides  into  the  valleys ;  or  else* 
springs  which  result  from  this  absorption,  under- 
mine the  soil  and  gradually  wash  it  away. 

The  rapid  increase  of  the  alluvial  deposits  of  the 
Hudson  River,  in  proportion  as  the  land  brought 
under  cultivation  is  increased,  is  an  example  in  point. 
Above  the  Highlands  of  the  Hudson,  for  150  miles, 
most  of  the  immediate  valley  of  the  river  is  formed 
of  clay  beds,  which  either  form  the  surface,  or  under 
19 


218  FOOD  OF  PLANTS. 

lie  it  at  a  small  depth.  Every  shower  removes 
large  quantities  of  the  finer  materials  from  the 
ploughed  fields,  and  transports  this  earthy  matter 
into  the  streams,  and  these  carry  more  or  less  into 
the  Hudson.  Deep  ravines  are  formed  in  the  clay 
lands,  and  they  extend  back  more  and  more  every 
year,  with  lateral  branches.  The  same  holds  true 
with  other  soils  than  the  clay,  where  they  are  loamy 
or  underlaid  by  rocks  which  are  impermeable  to 
water. 

FOOD  OF  PLANTS. 

It  is  now  a  well  ascertained  fact  that  particular 
mineral  substances  are  necessary  to  the  successful 
cultivation  of  particular  plants.  As  animals  thrive, 
or  drag  on  a  miserable  existence  according  to  the 
kind  and  quantity  of  nutriment  which  they  receive, 
so  with  plants ;  they  must  be  cultivated  in  such 
soils,  as  either  naturally  or  artificially  contain  such 
substances  as  are  calculated  to  afford  them  suitable 
nutriment,  else  they  cannot  thrive.  Wheat  for  in- 
stance,  will  grow  in  soils  which  do  not  contain  lime, 
but  it  is  well  known,  that  it  yields  a  crop  far  inferior 
in  quantity  and  quality  to  that  of  a  soil  similar  in 
every  respect,  except  that  of  its  containing  lime. 

We  do  not  intend  here  to  discuss  the  adaptation 
of  particular  plants  to  particular  soils;  we  may 
therefore  be  permitted  to  refer  the  reader  to  treatises 
on  agriculture  for  such  information. 

The  soil  is  dependent  to  a  great  extent  upon  the 
nature  of  the  subjacent  materials,  and  it  is  to  the 
mineralogical  texture  and  chemical  composition  rather 


POOD  OP  PLANTS.  219 

than  the  geological  age  of  rocks,  that  the  barrenness 
or  fertility  of  the  soil  is  due. 

Mr.  De  La  Beche,  one  of  the  distinguished  Eng- 
lish geologists,  very  justly  remarks.*  "  Taken,  how- 
ever, as  masses  of  matter,  the  mineralogical  struc- 
ture of  rocks  is  sufficiently  constant  throughout 
moderate  areas,  so  that  if  it  be  known  as  respects 
one  part  of  it,  the  other  parts  will  not  be  found  to 
differ  materially. 

Hence,  the  agriculturist  who  examines  a  good 
geological  map,  comprising  a  moderate  area,  may 
feel  assured  that  the  respective  soils,  upon  the  vari- 
ous rocks  traced  upon  it,  will  possess  the  same  gene- 
ral characters  under  equal  circumstances.  If  geolo- 
gical maps  be,  as  probably  they  will  be,  improved 
by  the  insertion  of  symbols  or  signs  in  different 
places,  showing  the  mineralogical  structure  of  the 
rocks  at  such  places,  the  information  afforded  to  the 
agriculturist  will  be  still  more  complete." 

"  a.  As  a  soil,  composed  of  the  same  mineral  sub- 
stances, is  of  very  different  value  to  the  agricultu- 
rist according  as  it  is  either  wet  or  dry,  the  observer 
should  direct  his  attention  to  those  circumstances 
which  render  it  either  the  one  or  the  other.  Dis- 
regarding for  the  present  the  general  surface-drain- 
age of  a  country,  the  dryness  of  a  soil  depends, 
under  equal  evaporation  and  supplies  of  rain,  upon 
the  facility  with  which  its  particles  permit  the  per- 
colation of  water  downwards,  and  this  facility  upon 
the  kind  of  rock  beneath,  as  above  noticed. 

Sandstone  rocks  generally  as  might  be  expected, 

*  De  La  Beche,  how  to  observe,  p.  286. 


220  FOOD  OF  PLANTS. 

afford  a  dry  soil.  This,  however,  is  not  the  case 
with  all  arenaceous  rocks.  In  some,  the  mineral 
matter,  cementing  the  particles  of  sand  together,  is 
so  aluminous  and  abundant,  that  when  the  rock  is 
decomposed,  the  clayey  matter  overpowers  the  sand, 
and  a  heavy  tenacious  soil  is  the  result. 

When  the  observer  finds  that  the  subjacent;  rock 
of  a  dry  soil,  is  porous,  and  sandy,  his  remedy  for 
this  kind  of  soil,  if  it  be  desirable,  will  be  to  do 

something  which  shall  retain  moisture  in  the  soil 

. 

itself  as  long  as  may  be  convenient ;  since,  once 
arrived  at  the  subjacent  rock,  it  will  be  absorbed 
freely  by  it. 

Some  addition  must  therefore  be  made  to  the  soil, 
either  of  a  substance  which  readily  absorbs  mois- 
ture from  the  atmosphere,  to  be  consumed  by  the 
vegetation,  or  of  a  mineral  substance  which  shall 
bind  the  particles  of  the  soil  more  firmly  together, 
so  that  in  a  given  time,  a  much  less  quantity  of 
water  shall  pass  downwards  to  the  absorbing  rock 
than  if  no  such  mineral  substance  had  been  added. 
Soils  thus  circumstanced  may  be  considered  as  well 
drained  beneath." 

"  When  a  dry  soil  is  the  produce,  by  decomposi- 
tion, of  a  rock  which  does  not  freely  absorb  water, 
additions  to  it,  for  the  purposes  of  rendering  it  more 
moist,  require  very  great  care.  The  observer  will 
generally  find  such  soils  shallow,  and  liable  to  be 
washed  away  by  rains.  The  rains  run  speedily  off 
where  the  physical  features  are  favourable,  and  the 
soil  soon  becomes  dry  from  evaporation. 

It  is  not  a  little  interesting  to  observe  the  excel- 
lent effect  produced  on  such  soils  by  the  loose  stones, 


FOOD  OF  PLANTS.  221 

not  unfrequently  scattered  over  them.  These  retain 
moisture  in  the  soil  by  preventing  the  evaporation 
which  would  otherwise  take  place ;  and  it  is  often 
not  a  little  curious  to  note  the  differences  of  corn- 
crops  on  two  adjacent  farms,  when  the  occupant  on 
one  has  removed  the  stones,  and  the  other  has  allow- 
ed them  to  remain,  the  advantage  being  so  greatly 
in  favour  of  the  latter. 

"  With  regard  to  scattered  stones  on  dry  soils  gene- 
rally, it  may  be  stated,  that  there  are  some  so  porous 
that  sufficient  moisture  would  not  remain  in  them 
to  reward  the  agriculturist  for  his  labour,  if  they 
were  not  abundantly  covered  with  scattered  stones. 
In  high  lands  they  also  serve  to  condense  fogs  and 
low  clouds,  and  thus  add  to  the  moisture  of  the  sub- 
jacent soil." 

"  b  A  wet,  or  heavy  soil,  mainly  depends  upon  the 
quantity  of  clayey  matter  afforded  by  the  rock  be- 
neath it.  The  latter  is  very  often,  under  such  cir- 
cumstances, a  clay  itself,  or  an  argillaceous  rock 
readily  converted  into  such  a  substance  by  the  ad- 
dition of  sufficient  moisture. 

"  The  soil,  therefore  is  held  up  by  a  sheet  of  rock 
I  impervious  to  water,  and  the  necessary  effects  must 
follow.  Such  soils  are,  however,  scarcely  ever  good 
in  themselves ;  but  a  good  soil  may  be,  and  occa- 
sionally is,  supported  by  a  bed  of  clay,  the  good 
soil  being  due  to  the  decomposition  of  a  bed  or 
stratum,  the  mineral  character  of  which  was  of  the 
proper  kind.  The  bed  of  clay,  or  other  bed  im- 
pervious to  water,  will,  if  the  soil  be  not  sufficient- 
ly thick,  cause  the  latter  to  be  wet,  and  unfit  for 
purposes  to  which  it  might  otherwise  be  dedicated. 
19* 


222 


FOOD  OF  PLANTS. 


"The  observer  should  ascertain  the  thickness  of 
the  clay  or  other  bed,  and  the  nature  of  the  rock 
beneath  it.  If  the  bed  of  clay,  supposing  it  to  be 
such,  is  not  too  thick,  and  the  stratum  beneath  be 
porous,  he  will  be  able,  from  the  geological  and  phy- 
sical characters  of  the  country,  to  judge  whether  it 
may  be  better  to  pierce  through  the  clay  bed,  in  many 
places,  leading  radiating  drains  to  the  holes  thus 
formed,  as  drain  generally  in  the  usual  way.  When 
there  is  an  extensive  and  elevated  table-land,  here 
and  there  cut  by  deep  valleys,  the  former  might  be 
the  cheaper  plan,  though  probably  it  has  never,  ex- 
cept accidentally,  been  carried  into  practice. 

"  We  have  seen  parts  of  a  table-land  formed  of  a 
fair  though  gravelly  soil,  a  resting  upon  a  tenacious 
clay,  6  drained  naturally 


upon  this  principle,  by 
means  of  pinnacles  of 
porous  rock,  c  c  which 
pierced  through  the  clay 
in  several  places,  and  entered  the  gravelly  soil  above. 
"  The  portions  of  soils  above,  and  near  the  pinnacles 
were  kept  fairly  drained  by  the  well  known  property 
of  porous  rocks  readily  to  absorb  moisture,  while 
those  portions  of  the  soil  which  were  too  far  from 
the  draining  influence  of  the  pinnacles,  were  wet 
and  heavy. 

"  If,  upon  the  same  principle,  an  agriculturist  should 
find  it  difficult  and  costly  to  drain  a  soil,  placed  un- 
der the  conditions  above  noticed,  in  the  usual  man- 
ner, and  that  the  part  to  be  drained  is  situated  as 
at  a,  if  he  can  deliver  the  water  into  the  porous  rock 


FOOD  OF  PLANTS. 


223 


e,  c,  by  drilling  numerous  holes  in  the  clay  bed  &,  b, 
such  water  would  tend  to  percolate  through  the  bed 
c,  c,  and  be  delivered  in  springs  into  the  valleys  v,  v, 
if  c,  c,  be  supported  by  a  bed  d,  d,  impervious  to 
water.  If  the  water  be  not  stopped  by  such  a  bed, 
then  it  will  continue  to  percolate  through  the  infe- 
rior mass  in  the  usual  manner.  To  know  that  the 
proper  conditions  obtain,  necessarily  requires  com- 
petent geological  observation." 

"  c  When  an  observer  finds  a  heavy  soil  produced 
by  the  decomposition  of  hard  rocks,  such  as  certain 
sandstones  and  slates  of  the  grauwacke  series,  or 
others  of  the  like  mineralogical  structure,  be  their 
geological  age  what  it  may,  he  should  direct  his  at- 
tention to  the  stratification  of  the  rocks  affording 
the  principal  materials  for  the  soil,  since  the  prac- 
ticability of  ameliorating  the  latter  much  depends 
upon  this  circumstance. 

"  Let  us  suppose  that  the  annexed  section  repre- 
sents the  stratification  of  a  series  of  rocks  affording 
a  heavy  clay  soil,  so  that  the  beds  are  horizontal  at 

0,  contorted  at 
b,  and  dip  at 
a  considerable 
angle  at  c. 
Nowsuppos- 


224  FOOD  OF  PLANTS. 

ing  them  to  be,  as  they  generally  are,  nearly  imper. 
vious  to  water  as  beds,  and  that  the  soil  is  attempted 
to  be  made  lighter  by  artificial  means  over  the  whole 
surface  a,  b,  c,  very  different  success  will  attend  the 
experiment  at  a,  and  at  c,  because  a  water  support- 
ing  surface  will  still  continue  beneath  the  soil  at  a, 
while  the  interstices  between  every  bed  at  c9  will 
serve  to  drain  the  land. 

"  Consequently,  if  the  soil  be  so  lightened  that 
water  can  freely  percolate  down  to  the  edges  of  the 
beds  at  c,  due  care  being  taken  to  lay  open  such  by 
lines  of  drains,  so  that  the  upper  portions  of  the  in. 
terstices  are  not  choked  by  particles  of  clay,  the 
soil  may  be  rendered  far  more  dry  than  before. 

"  If  an  observer  direct  his  attention  to  two  soils 
derived  from  similar  rocks,  the  one  situated  upon 
nearly  horizontal  strata,  and  the  other  upon  the 
edges  of  highly  inclined  beds,  he  will  frequently  per- 
ceive that  the  former  may  be  heavy  and  the  latter 
comparatively  light,  for  the  simple  reason  that  one 
is  naturally  drained  and  the  other  not." 

"  d  Although  a  geologist  may  feel  satisfied  that 
porous  rock  is  situated  beneath  a  water  supporting 
stratum,  near  the  surface  of  land,  the  agriculturist 
can  scarcely  be  expected  to  be  aware  of  the  struc- 
ture of  the  rocks  beneath  the  few  feet  to  which,  in 
his  deepest  ditches,  he  is  in  the  habit  of  working. 

"  He  may,  however,  greatly  advance  himself  in  a 
knowledge  of  circumstances  that  may  often  prove 
highly  valuable  to  him,  by  consulting  good  geologi- 
cal maps,  constructed  on  a  large  scale,  which  will 
give  him  the  surface  of  land  occupied  by  any  given 
rock,  and  then  turn  to  the  sections  which  ought  to 


FOOD  OF  PLANTS.  225 

accompany  such  maps,  which  will  show  him  how  the 
rocks  occur  relatively  to  each  other  beneath  the  soil. 

"Let  him  now  consult  the  memoirs  written  to  illus- 
trate  the  map  and  sections ;  and  by  carefully  com- 
bining the  accounts  given  of  the  structure  and  com- 
position of  the  rocks,  as  noticed  in  the  memoirs, 
first,  with  their  relative  position  as  shown  in  the 
sections,  and  secondly,  with  the  portions  of  surface 
occupied  by  each  respectively,  as  shown  by  the 
maps,  he  will  obtain,  without  embarrassing  himself 
with  those  questions  which  relate  to  the  higher 
branches  of  geology,  a  stock  of  knowledge  respect- 
ing the  rocks  beneath  the  soil  in  given  districts, 
which  he  can  readily  turn  to  good  account  in  his 
management  of  land,  even  when  the  authors  of  the 
maps,  sections,  and  memoirs  may  not'  have  con- 
structed the  former,  or  written  the  latter,  with 
reference  to  any  advantage  agriculture  could  derive 
from  geology. 

"  e  Even  a  knowledge  of  the  faults  which  frequent- 
ly traverse  countries  may  be  turned  to  account  by 
an  agriculturist  in  the  drainage  of  land.  Some  of 
these  fissures  or  dislocations  are  pervious  to  water, 
and  act  as  main  drains  to  portions  of  country,  as  is 
well  known  to  their  cost  by  miners  in  metalliferous* 
districts.  Others  are  filled  with  substances,  such 
as  clay,  which  prevent  the  passage  of  water  on  one 
side  of  the  fault  to  the  others ;  a  circumstance  highly 
valuable  in  some  coal  districts, — for  by  the  intersec- 
tion of  several  of  these  faults,  masses  of  strata  are 
enclosed  by  them,  and  if  the  water  be  pumped  up  by 
proper  engines  from  such  masses  respectively,  the 
coal-worker  has  only  to  contend  with  the  water  in 


226  FOOD  OF  PLANTS. 

any  mass  on  which  he  may  be  occupied,  a  supply 
from  other  adjacent  masses  being  cut  off  by  the  sur- 
rounding faults.  It  is  obviously  from  the  first  kind 
of  faults  that  the  agriculturist  can  derive  any  advan- 
tage in  the  shape  of  drainage. 

"  Faults  may  be  made  to  assist  the  drainage  of 
elevated  table-lands,  even  when  their  continuations 
across  the  valleys,  which  may  cut  into  such  table- 
lands, afford  an  abundant  supply  of  water  to  the 
surface,  as  will  be  seen  by  the  annexed  diagram. 


Let  the  line  a,  Z>,  be  a  level,  at  which  a  fault  contains 
an  abundance  of  water,  which  is  readily  discharged 
upon  the  surface  of  the  valleys  i?,  u,  that  cut  the  sur- 
face of  land  beneath  this  level.  Then  if  c,  d,  be 
table-lands  into  which  the  fault  cuts  upwards,  the 
water  conducted  into  it  on  such  table-lands,  either 
naturally  or  artificially,  will  tend  to  percolate  down- 
wards to  the  level  whatever  its  relative  height  may 
be,  at  which  a  quantity  of  water  is  sustained  in  the 
fissures,  and  which  we  have  supposed  to  be  repre- 
sented by  the  line  a,  6." 

"f  As  the  nature  of  a  soil  so  materially  depends 
upon  the  mineral  composition  and  structure  of  the 
rock  beneath  it ;  an  agriculturist  should  be  alive  to 
the  advantages  he  may  derive  from  a  mixture  of  the 
materials  of  two  or  more  rocks,  in  producing  a  soil, 
which  shall  be  better  than  that  naturally  found  on 
either  respectively. 


FOOD  OF  PLANTS.  227 

"  This  sometimes  is  done*  when  that  kind  of  rock 
commonly  known  as  marl  is  near  some  soil  to  which 
it  is  considered  a  valuable  addition  ;  the  marl  being 
taken  from  the  marl  rock  and  distributed  over  the 
soil.  In  this  the  agriculturist  does  no  more  than 
add  mineral  matter  to  his  soil ;  which,  in  point  of 
fact,  had  not  been  afforded  either  at  all,  or  in  the 
proper  quantity,  by  the  decomposition  of  the  rock 
beneath  it. 

"  Many  other  valuable  mixtures  than  these  might 
be  made  from  the  materials  of  rocks,  frequently  ad- 
jacent to  each  other,  either  as  regards  the  surface  of 
land,  or  depth  beneath  such  surface.  Some  of  these 
mixtures  are  so  obvious,  that  while  examining  the 
geological  structure  of  some  countries,  we  have  been 
surprised  that  the  accidental  mixtures  of  the  com- 
ponent parts  of  two  adjacent  rocks  at  the  lines  of 
their  junction,  and  which  demonstrate  by  their  ad- 
vantages the  superior  fertility  upon  them,  have  not 
induced  agriculturists  to  inquire  a  little  into  the 
cause  of  them. 

"  Carbonate  of  lime  cannot  naturally  exist  in  soils 
derived  from  rocks  which  do  not  contain  it, — at  least 
any  portion  found  in  them  must  be  derived  from  the 
remains  of  snail-shells  and  the  like.  Now,  the  rocks  * 
which  do  not  contain  carbonate  of  lime  are  very 
numerous,  particularly  among  a  variety  of  the  older 
series  ;  and  as  the  presence  of  carbonate  of  lime  in 
a  soil  is  so  valuable  to  the  agriculturist,  it  is  ob- 
viously a  mineral  substance  which  it  becomes  his 
interest  to  add  to  one  that  contains  little  or  none 
of  it. 

«  The  application  of  lime  in  its  burnt  state  to  soils 


228  FOOD  OF  PLANTS. 

is  so  common,  that  we  should  not  notice  the  fact  if 
we  had  not  often  witnessed  farmers  dosing  their  land 
to  excess  with  it,  without  the  smallest  regard  to  any 
other  mineral  ingredient,  or  to  those  proportions  ot 
such  ingredients  which  have  been  found  to  answer 
but  with  different  kinds  of  cultivation.  Indeed,  as 
far  as  regards  the  large  majority  of  farmers,  they 
seem  to  consider  that  all  plants  are  to  be  fed  alike, 
and  that  what  is  good  for  one  must  be  so  for  ano- 
ther." 

"  g  Given  rocks,  viewed  mineralogically,  afford- 
ing like  soils  by  their  surface  decomposition,  the  ob- 
server should  direct  his  attention  to  the  various 
plants  which  flourish  best  on  each  respectively, 
according  to  the  climates  in  which  they  may  be 
situated.  This  subject  which  may  be  termed  geolo- 
gical botany,  has  already  been  advanced  by  many 
local  researches,  but  hitherto  no  very  extended  views 
have  been  found  upon  them.  It  can  scarcely  be 
otherwise  than  one  in  which  agriculturists  should  be 
deeply  interested. 

"  In  this  way,  some  plants  are  found  to  be  of  little 
value  when  cultivated  off  given  rocks.  The  pimento 
or  allspice  tree  of  Jamaica  may  be  taken  as  a  good 
instance  of  this  fact,  since  it  is  only  profitably  cul- 
tivated upon  the  white  limestone  formation  of  that 
island.  Again,  other  kinds  of  cultivation,  though 
they  may  to  a  certain  extent  succeed  on  several 
kinds  of  rocks,  are  found  to  afford  far  more  profit- 
able returns  upon  one  or  two  in  particular. 

"  Even  alluvial  soils  differ  in  value,  as  might  indeed 
be  anticipated,  since  patches  of  them  are  respective- 
ly formed  of  the  wash,  if  we  may  use  the  expression, , 


ROADS.  229 

of  districts  which  may,  and  generally  do  vary  as  to 
the  rocks  of  which  they  are  composed. 

"  Some  soils  are  underrated  because  they  will  not 
readily  afford  good  returns,  as  regards  all,  or  the 
greater  part,  of  the  cultivation  attempted  upon  them. 
We  will  not,  however,  occupy  more  of  our  space 
with  this  subject.  The  connexion  of  the  'due  of 
the  soil  and  the  kind  of  rock  beneath  it,  will  con- 
stantly be  forced  upon  the  observer,  and  he  lias  only 
to  register  and  classify  such  facts  to  obtain  a  fund 
of  valuable  information  on  this  head," 


II.  ROADS, 

"  That  the  expense  of  constructing  a  new  road,  or 
of  maintaining  an  old  one  in  good  order,  greatly  de- 
pends upon  the  kind  of  ground  under  it,  upon  the 
facility  with  which  proper  stone  may  be  obtained 
for  it,  and  upon  the  stability  of  the  various  cuts 
which  it  may  be  found  necessary  to  make  in  the 
rocks,  is  well  known.  It  is  not,  however,  so  well 
known  that  these  circumstances  depend  upon  the* 
geological  structure  of  a  country,  and  that  a  know- 
ledge of  this  structure  would  enable  those  who  pos. 
sessed  it  to  determine  whether  one  line  of  new  road 
would  be  more  costly  than  another ;  whether,  when 
it  becomes  a  question  to  patch  up  an  old  line  of 
road  or  construct  a  new  one,  the  one  or  the  other 
will  be  ultimately  found  least  expensive ;  and  that 
some  kinds  of  stone  should  be  employed  upon  roads 
20 


230  ROADS. 

in  preference  to  others,  when  several  kinds  can  be 
readily  obtained." 

"  Roads  generally  are  planned  with  regard  to  lit- 
tle else  than  levels  and  distances  ;  and  if  there  be  a 
small  advantage  in  this  respect  between  two  lines  in 
favour  of  one,  that  line  will  be  selected,  though  often 
a  fair  amount  of  geological  knowledge  would  be  suf- 
ficient to  show  that  the  expense,  not  only  of  form- 
ing, but  also  of  keeping  up  this  road,  will  be  far 
greater  than  for  the  other.  Good  geological  maps 
are  in  this  respect  highly  valuable,  as  they  enable 
those  who  have  to  decide  upon  subjects  connected 
with  roads  to  see  at  once  the  kind  of  rocks  over 
which  a  projected  line  of  road  is  intended  to  pass. 
They  also  point  out  the  proximity  of  rocks  which 
may  afford  good  materials  for  stoning  either  new  or 
old  roads." 

"  a  In  cutting  through  stratified  rocks,  it  should 
be  recollected  that  lines  of  springs  may  be  inter- 
sected which  may  prove  injurious  to  the  road  ;  and 
also  that,  by  inattention,  a  hard  supporting  stratum 
may  be  cut  through,  and  the  road  thrown  upon  a 
clay  or  other  loose  substance,  by  which  much  un- 
necessary expense  will  be  incurred  in  order  to  ren- 
der the  bottom  firm.  In  all  deep  cuttings  to  lower 
hills,  the  observer  should  note  the  mineral  structure 
of  the  rock  cut  through,  so  that,  when  it  becomes 
exposed  to  the  atmosphere,  the  slopes  given  to  the 
sides  may  be  found  sufficient,  and  the  drainage  of 
the  road  preserved." 

"  b  In  choosing  materials  for  macadamized  roads, 
the  observer  should  recollect  that  the  stones  placed 
on  them  are  exposed,  not  only  to  friction,  but  also 


ROADS.  231 

to  the  pounding  or  crushing  action  of  the  weights 
which  roll  over  them,  and  consequently  that  a  tough 
as  well  as  hard  substance  is  required.  Now,  rocks 
differ  exceedingly  in  these  qualities  ;  and  those  per- 
sons who  have  paid  attention  to  the  kind  of  stones 
thrown  on  roads  must  have  remarked  how  frequently 
hard  stones  are  preferred  by  surveyors  and  others, 
when  tough  materials  were  to  be  obtained  equally 
near  and  cheap.  Rocks  which  are  composed  of 
substances  of  unequal  degrees  of  toughness,  are 
greatly  inferior  to  those  which  are  of  the  same  tex- 
ture throughout :  thus  granites  generally  afford  road- 
stones  inferior  to  a  great  variety  of  trappean  rocks. 
Such  roads  soon  become  either  dusty  or  muddy, 
according  to  the  weather. 

"Those  granites  in  which  the  feldspar  is  well  crya- 
talized  are  the  worst  for  the  purposes  of  stoning  roads, 
since  this  mineral  then  soon  crumbles  under  pres- 
sure, while  the  granites  in  which  hornblende  pre- 
vails, and  the  feldspar  is  more  compact,  are  the  best 
The  trappean  rocks  vary  considerably  in  their  value 
as  road-stones ;  even  the  same  quarry  will  afford 
materials  of  different  degrees  of  toughness.  Some 
greenstones  are  particularly  valuable  in  this  respect,* 
as  also  certain  diallage  and  hypersthene  rocks. 

"  When  no  better  instrument  is  at  hand,  a  large 
iron  pestle  and  mortar  may  be  used  with  advantage 
in  ascertaining  the  relative  toughness  of  stones.  If 
an  observer  will  take  specimens  of  those  intended 
for  examination,  of  the  size  of  the  stones  usually 
thrown  on  the  roads,  and  then  proceed  to  pound 
them,  taking  one  specimen  at  a  time,  he  will  soon 
obtain  a  rough  estimate  of  their  relative  values. 


232  EOADS. 

Machines  for  ascertaining  the  relative  superiority 
of  road -stones  have  been  invented,  and  there  would 
be  no  difficulty  in  constructing  those  which  would 
show  their  relative  degrees  of  toughness  with  con- 
siderable precision. 

"  By  stoning  a  road  with  proper  tough  materials, 
we  not  only  reduce  the  expences  of  its  maintainance 
but  also  the  annual  amount  of  hindrance  caused  by 
the  more  frequent  supply  of  rough  new  stones,  which 
tend  so  much  to  retard  the  progress  of  wheel-car- 
riages, and  add  to  the  labour  of  the  horses  that  draw 
them." 

"  c  The  difference  in  the  durability  of  road  ma- 
terials, obtained  from  different  beds  of  the  stratified 
rocks,  is  so  considerable,  that  those  charged  with 
their  supply,  in  districts  where  such  rocks  prevail, 
should  make  themselves  acquainted  with  their  strike 
and  dip.  The  instances  in  which  much  unneces- 
sary expense  might  be  avoided,  by  this  simple  ap- 
plication of  geological  knowledge,  are  far  more 
numerous  than  would  readily  be  credited  by  those 
who  have  not  directed  their  attention  to  the  sub- 
ject." 

"  d  In  all  cases,  whether  of  stratified  or  massive 
rocks,  the  observer  should  be  careful  that  the  stones 
employed  for  roads  are  not  taken  from  the  upper  or 
weathered  portions  of  quarries,  where  they  have  been 
more  or  less  exposed  to  atmospheric  decomposing 
causes,  and  consequently  are  not  so  valuable  for  the 
purposes  required  as  those  taken  from  situations 
where  these  decomposing  causes  have  scarcely  been 
felt." 

"  e  In  cutting  roads  on  the  sides  of  hills,  the  ob- 


ROADS. 


233 


server  should  in  many  cases  note  the  dip  of  the  beds, 
and  their  general  structure,  if  the  subjacent  rocks 
be  stratified,  with  considerable  care ;  otherwise  much 
mischief  may  ensue. 

"  Let  the  annexed  diagram  represent  the  section 
of  a  hill,  composed  of  beds  which  dip  in  one  direc- 

d    b 


tion.  Let  c,  d,  be  a  bed  of  sandstone  resting  upon 
a  soft  clay,  a,  b.  Now  if  a  cut,  e,  be  made  in  the 
hill,  the  continuity  of  c,  d,  will  be  destroyed,  and 
the  part  d,  will  tend  to  slide  down  upon  the  cut  e. 
If  a  cut,/,  be  made  on  the  other  side  of  the  hill,  and 
a  similar  arrangement  of  beds  exist  there,  no  such 
tendency  of  the  upper  to  slide  upon  the  lower  beds 
will  be  produced. 

"  Hence  not  only  in  such  instances  as  that  above 
noticed,  but  also  in  districts  of  certain  slate  and 
other  rocks,  where  the  cohesion  between  the  laminae 
orbed  is  slight,  and  the  dipsomewhat  highly  inclined, 
a  preference  should  be  given,  when  cuts  are  made 
for  roads,  to  those  sides  of  valleys  or  hills  as  the  case 
may  be,  where  the  strata  dip  inwards  into  the  mass 
of  the  hill  or  mountain  as  at/." 

20* 


234  CANALS. 


III.  CANALS. 

"  In  projecting  lines  of  canals,  particularly  when 
tunnels  are  to  be  constructed,  a  knowledge  of  the  ge- 
ological structure  of  the  country  is  not  less  necessary 
than  in  the  case  of  roads.  The  probability  of  meet- 
ing  with  springs  of  water,  the  porous  or  impervious 
character,  as  regards  water,  of  the  rocks  to  be  tra- 
versed, and  the  kinds  of  rock  which  will  be  encoun- 
tered in  cutting,  may  all  in  a  great  degree  be  fore- 
seen by  those  who  have  examined  the  geological 
structure  of  the  district. 

"  Hence  good  geological  maps  will  be  found  of 
great  value  to  those  who  are  about  to  form  canals. 
They  also  point  out  the  various  mineral  substances 
which  may  advantageously  be  brought  to  the  canal 
for  the  purposes  of  traffic.  From  a  knowledge  of 
this  kind,  canals  have  been  made  to  pass  by  or 
through  tracts  of  country  where  lime  stones,  coal, 
or  metals  are  discovered." 

"  Canals,  as  is  well  known,  are  often  found  to  be 
more  costly  than  was  anticipated,  from  the  simple 
fact  that  some  of  the  rocks  traversed,  readily  absorb 
water,  and  it  therefore  becomes  necessary  to  incur 
the  expense  of  rendering  the  canal-bed  water-tight. 

"  Where  the  supply  of  water  is  limited,  the  pres- 
ence of  an  extended  line  of  porous  rock  is  a  serious 
difficulty.  It  is  one,  however,  which  might  some- 
times be  avoided  by  a  competent  knowledge  of  the 
geological  structure  of  the  district  traversed,  for 
such  knowledge  would  enable  the  engineer  so  to  form 


WELLS.  235 

his  plan  as  to  avoid  the  porous  rocks  as  much  as 
possible. 

"  It  should  be  recollected  that  a  knowledge  of  the 
rocks  on  the  surface  will  not  give  that  of  those 
which  may  be  cut  into  the  line  of  a  canal,  unless  it 
be  coupled  with  such  information,  respecting  the 
mode  in  which  the  rocks  of  the  district  occur,  that 
the  observer  shall  be  aware  of  those  kinds  which 
will  probably  be  found  at  given  depths  in  different 
places.  A  fine  retentive  clay  may  exist  on  the  sur- 
face and  rest  upon  a  porous  sandstone ;  and  there- 
fore, in  following  the  levels,  the  former  may  be  cut 
through,  and  the  canal-bed  be  based  on  the  latter." 


IV.  WELLS. 

"  The  geological  observer  will  find  no  difficulty 
in  applying  his  knowledge  to  the  probability  or  im- 
probability of  obtaining  water  by  means  of  wells  in 
given  situations.  The  most  important  are  those 
named  Artesian,  which  are  perpendicular  borings 
made  into  the  earth  to  various  depths,  and  from 
which  large  and  constant  supplies  of  water,  which 
flow  over  the  land  in  streams,  are  often  procured  in 
districts  where  this  necessary  of  life  is  otherwise 
obtained  either  of  bad  quality  or  in  small  quanti- 
ties." 

"  a  The  observer,  neglecting  those  springs  of  wa- 
ter which  rise  from  faults,  and  those  which  gush  out 
in  greater  or  less  abundance  from  limestone  and 
other  cavernous  rocks,  has  only  to  recollect  that  the 


236  WELLS. 

more  common  springs  are  produced  by  the  percola- 
tion of  rain-water  through  porous  to  impervious 
beds,  where  they  are  stopped,  and  he  will  readily  be 
enabled  to  judge  of  the  facility  or  difficulty  there 
may  be  in  procuring  water  by  means  of  wells  in  a 
given  district. 

"  Let  the  annexed  sketch  represent  the  section  of 

1 


a  hill  composed  of  a  porous  siliceous  sandstone  a, 
a  clay  bed  b,  a  porous  and  somewhat  calcareous 
sandstone  c,  and  another  clay  d,  and  the  rocks  be 
uncovered  by  gravel  in  the  valley  f,  while  porous 
gravel  is  found  in  the  valley  g. 

"  Now,  to  obtain  water  by  means  of  wells  it  would 
be  necessary  to  sink  through  a  on  the  top  of  the 
hill  to  the  clay  b,  where  the  rain-water  which  has 
percolated  through  a  will  be  stopped.  This  line  of 
water  will  probably  be  shown  by  a  line  of  springs 
in  the  valley  f;  but  the  springs  which  will  equally 
flow  from  it  in  the  valley  g  (for  the  sake  of  illustra- 
tion we  suppose  the  strata  horizontal)  will  be  con- 
cealed beneath  the  gravel  e,  and  will  percolate  be- 
tween the  clay  and  it  to  the  porous  sandstone  c,  on 
that  side. 

"  A  well  therefore  formed  at  2,  through  the  gravel, 
would  reach  the  same  line  of  water  as  is  obtained 
at  1,  and  forms  springs  in  the  valley  f.  A  well 
pierced  at  3  in  the  valley /would  afford  the  water 


WELLS.  237 

stopped  by  the  clay-bed  d,  and  the  water  in  it  would 
probably  differ  in  quality  from  that  obtained  in  the 
line  above  6,  because  it  has  traversed  a  different 
kind  of  rock. 

"  To  reach  the  same  line  of  water  in  the  valley  g, 
it  would  be  necessary  to  pierce  through  the  gravel 
e,  and  the  sandstone  c ;  and  if  a  thin  clay  parting 
should  separate  e  from  c,  derived  from  the  bed  b  in 
that  direction,  the  well  4  would  first  give  the  line  of 
water  above  b,  and  afterwards  that  above  d." 

66  b  The  observer  will  readily  conceive  a  variety 
of  circumstances  which  may  modify  a  supply  of 
well-water  in  different  localities ;  but  by  paying 
attention  to  the  geological  structure  of  each,  so  as 
to  obtain  a  knowledge  of  the  true  relative  positions 
of  the  porous  and  impervious  beds,  the  influence  of 
faults,  if  such  occur,  being  duly  considered,  he  will 
find  little  difficulty  on  this  head." 

"c  Care  should  be  taken,  when  the  impervious 
bed  supporting  a  line  of  water  is  thin,  not  to  cut 
through  it ;  for  by  so  doing  the  water  will  be  let 
out  into  the  rock  beneath,  if  that  be  porous." 

"d  Among  highly  inclined,  and  even  vertical 
strata,  water  may  sometimes  be  obtained  at  diffe- 
rent levels,  from  the  saturation  of  slate  or  other  beds 
to  a  certain  degree  pervious  to  water  at  such  levels  ; 
so  that  if  a  well  be  formed  in  such  situations,  the 
water  will  percolate  into  the  cavity  and  fill  it  up  to 
the  height  to  which  the  line  of  saturation  extends. 
The  observer  may  frequently  find  little  cavities 
formed  in  highly  inclined  or  vertical  beds  of  slate, 
in  the  vicinity  of  cottages  in  slate  districts,  which 
are  filled  on  this  principle." 


238  MINING. 


V.  MINING. 

"  It  is  not  our  intention  to  enter  upon  the  com- 
plicated subject  of  mining,  further  than  to  point  out 
the  necessity  of  geological  knowledge,  on  the  part 
of  those  who  seek  metals  or  coals  in  districts  where 
they  have  not  been  hitherto  found.  The  sums  of 
money  thrown  away,  more  particularly  in  the  search 
of  coal,  which  this  knowledge  would  have  saved,, 
must  be  collectively  very  considerable.  A  little 
black  shale,  or  a  piece  of  lignite,  is  often  sufficient 
to  cause  the  expenditure  of  thousands,  in  localities 
where  there  is  not  the  slightest  probability  of  suc- 
cess. 

"  In  the  search  for  metals,  matters  are  frequently 
not  much  better.  It  may  be  true,  and  *no  doubt  is 
so,  that  particular  metals  and  coal  are  not,  as  waSy 
once  supposed  confined  (viewing  the  surface  of  the 
earth  generally)  to  rocks  formed  at  particular  geolo- 
gical epochs ;  but  it  may  be  safely  stated  that,  in 
given  areas,  both  metals  and  coal  will  be  found  to 
have  given  geological  positions." 

"  a  In  the  search  for  coals,  observers  should  be 
guided  by  the  knowledge  of  the  geological  structure 
of  given  areas,  in  whatever  part  of  the  world  these 
areas  may  occur.  A  knowledge  of  the  general 
geological  structure  of  eastern  Australia  will  no 
doubt  one  day  enable  the  geologists  of  that  country 
to  direct  the  search  for  coal  in  given  rocks,  and  to 
advise  the  discontinuance  of  them  in  others,  pre- 
cisely as  English  geologists  would  advise  the  search 


MINING.  239 

for  coal  in  the  proper  places,  and  tell  those  who  seek 
for  it  in  numerous  other  situations  where  it  has 
been  sought,  that  they  were  throwing  away  time, 
labour  and  money." 

"  b  With  regard  to  metals,  a  knowledge  of  the 
geological  structure  of  given  areas  is  also  requisite. 
As  the  rocks  of  the  same  epoch  often  change  their 
mineral  character  in  horizontal  distances,  so  also  their 
metalliferous  character  is  found  not  to  be  constant 
throughout  extensive  areas.  A  due  consideration 
of  this  subject  would,  however,  lead  us  into  discus, 
sions  foreign  to  the  object  of  this  work.  It  will  be 
sufficient  to  state,  that  the  knowledge  of  the  geolo- 
gical structure  of  the  British  Islands,  France,  Ger- 
many, or  any  other  country,  will  enable  the  geolo- 
gical observers  in  their  respective  portions  of  the 
earth's  surface  to  state,  that  given  rocks,  or  given 
modes  of  their  occurrence,  may  afford  useful  metals, 
while  in  other  rocks  or  situations  the  search  for 
them  can  scarcely  be  otherwise  than  fruitless." 

"c  We  may  here  notice  the  singular  circum- 
stance, that  in  this  country,  where  so  much  capital 
is  invested  in  metalliferous  mines  and  collieries, 
there  should  be  no  national  school,  or  college  of 
mines,  though  the  great  utility  of  such  establish-, 
ments  is  amply  proved  by  experience  in  foreign 
countries,  where  for  the  most  part  the  capital  thus 
invested  is  comparatively  trifling.  British  miners 
and  coal- workers  are  compelled  to  pick  up  their  in- 
formation how  they  can.  If  by  good  fortune  young 
men  are  placed  under  those  who  value  science,  and 
are  aware  of  the  advantages  which  may  be  derived 
from  it,  they  have  certainly  little  reason  to  com- 


240  BUILDINGS. 

plain  ;  but,  unfortunately  this  is  not  the  lot  of  the 
many.  A  college  of  mines,  properly  conducted, 
would  be  alike  beneficial  to  those  who  invest  their 
money  in  mines  and  collieries,  and  those  who  work 
them.  It  could,  indeed,  scarcely  be  otherwise  than 
a  national  benefit.  Hitherto,  however,  the  attempts 
which  have  been  made  to  call  the  attention  of  govern- 
ment to  this  subject  have  been  unsuccessful." 


VI.  BUILDINGS. 

"  Disregarding  private  dwellings,  on  which  such 
various  materials  are  employed,  according  to  the 
motives  that  lead  to  their  erection,  it  may  be  fairly 
stated,  that  a  knowledge  of  the  general  structure  of 
rocks,  and  the  situations  whence  the  best  materials 
may  be  obtained,  is  essential  to  those  who  are  either 
charged  with,  or  direct,  public  works.  A  stone 
which  may  be  sufficiently  durable  if  plunged  beneath 
water,  may  not  be  so  when  kept  alternately  wet  and 
dry  by  the  rise  and  fall  of  water  in  a  river  or  on  a 
tidal  coast,  or  when  wholly  exposed  to  the  action 
of  the  atmosphere.  A  somewhat  porous  sandstone, 
for  instance,  may  do  well  when  kept  constantly  un- 
der-water  ;  but  the  same  rock  when  exposed  to  the 
atmosphere,  more  particularly  in  climates  subject 
to  frost,  might  gradually  crumble  away  from  causes 
previously  noticed." 

"  a  The  observer  desirous  of  selecting  a  stone  to 
be  exposed  to  atmospheric  influences  would  do  well 
to  study  the  mode  in  which  it  is  weathered  in  the 


BUILDINGS.  241 

locality  whence  it  is  obtained.  He  may  learn  which 
part,  if  it  be  a  compound  rock,  is  liable  to  give  way 
before  such  influences,  and  the  conditions  under 
which  it  does  so.  Granite  generally  is  considered 
a  proper  material  for  national  monuments.  Some 
granites,  however,  though  they  may  be  hard  and 
difficult  to  work,  when  first  taken  from  the  quarry, 
are  among  the  worst  building  materials,  in  conse- 
quence of  the  facility  with  which  the  feldspar  in 
them  decomposes,  when  exposed  to  the  action  of  a  wet 
atmosphere,  in  a  climate  which  may  be  warm  dur- 
ing part  of  the  year,  and  cold  during  the  other." 

"  Rocks  which  readily  absorb  moisture,  such  as 
many  of  those  which  are  termed  free  stones,  are  ex- 
ceedingly bad  for  the  external  portions  of  exposed  pub- 
lic buildings  ;  since  in  countries  where  frosts  occur, 
the  freezing  of  the  water  in  the  wet  surface  continual- 
ly peels  off  the  latter,  and  eventually  destroys  the  or- 
namental work  carved  upon  it.  It  should  be  recol- 
lected that  free  stones,  so  termed  because  they  are 
easily  worked,  are  often  valued  because  they  may 
be  cut  readily  when  first  taken  from  the  quarry,  and 
subsequently  become  harder  when  exposed  to  the 
atmosphere ;  and  that  this  quality  arises  from  the 
evaporation  of  the  water  contained  in  the  stone 
when  forming  part  of  the  natural  rock.  Now,  some 
of  these  freestones  again  readily  absorb  moisture, 
while  others  do  not :  hence  the  latter  should  be  pre- 
ferred ;  and  an  observer  should  ascertain  this  fact 
by  experiment  before  any  given  freestone  is  se- 
lected." 

"  Some  freestones  are  formed  of  particles  of  sand 
cemented  together  by  different  substances,  the  ce- 
21 


242  BUILDINGS. 

meriting  matter  being  sometimes  siliceous,  at  others 
calcareous,  and  at  others  again  formed  of  oxide  of 
iron.  In  the  first  case,  the  freestone  would  not 
suffer  from  the  chemical  action  of  atmospheric  in- 
fluences  upon  it ;  while  in  the  second,  rain-water 
containing  carbonic  acid  would  tend  to  dissolve  the 
calcareous  matter,  and  deprive  the  sand  of  its  ce- 
ment ;  and  in  the  third,  the  action  of  atmospheric 
influences,  would  tend  to  render  the  material  un- 
sightly by  staining  it  with  iron-rust." 

"  The  little  attention  that  has  been  paid  in  the 
erection  of  national  monuments  in  this  country,  to 
the  durability  of  the  materials  of  which  they  are 
constructed,  is  well  known.  There  is  no  want  of 
good  materials,  if  they  would  be  sought  out ;  and  it 
often  occurs  to  the  geologist  to  find  them." 

"  b  In  selecting  stone  for  artificial  harbors,  break- 
waters, quays,  and  bridges,  the  observer  should  note 
those  lands  which  best  suit  the  different  parts  of 
the  work  to  be  executed.  Where  a  pier  or  break- 
water has  to  resist  the  action  of  heavy  breakers, 
charged  with  the  pebbles  of  a  beach,  a  harder  ma- 
terial  becomes  necessary  than  when  it  has  only  to 
encounter  the  action  of  breakers  not  so  charged, 
In  both  cases  the  weight  of  a  stone  is  an  important 
consideration,  since  the  greater  the  weight  in  the 
same  bulk,  the  greater  the  resistance  to  removal  from 
the  flow  of  a  breaker,  other  things  being  equal.  An 
observer,  therefore,  should  ascertain  the  specific 
gravity  of  a  stone  he  may  be  desirous  of  employing. 
Several  kinds  of  stone,  otherwise  equally  good,  may 
f  vary  much  in  this  respect ;  so  that  a  pier  of  given 


BUILDINGS.  243 

dimensions  may  differ  considerably  from  another  in 
weight  according  to  the  material  employed." 

"  In  constructing  piers,  quays,  and  bridges,  where 
the  water  level  varies,  materials  which  may  be  good 
for  one  part  of  the  work  may  not  be  so  for  other 
portions.  Many  rocks  which  may  be  advantage- 
ously employed  in  situations  constantly  under  wa- 
ter, will  be  found  liable  to  decomposition  when  ex- 
posed to  the  atmosphere,  particularly  in  those  por- 
tions kept  alternately  wet  and  dry  by  the  rise  and 
fall  of  tides,  or  other  causes  producing  changes  in 
the  level  of  the  water.  An  observer  may  often  ob- 
tain information  on  this  head,  by  studying  the  con- 
dition of  rocks  on  the  banks  of  rivers,  and  on  the 
sea-shore,  and  geologists  are  thus  frequently  aware 
of  many  situations  where  quarries  for  the  purposes 
iibove  mentioned  may  be  advantageously  opened."* 

*  De  La  Beche,  how  to  observe. 


SKETCH 

OF   THE 

HISTORY  OF  GEOLOGY. 


We  learn,  that  the  speculative  part  of  Geology, 
engaged  the  attention  of  mankind  at  a  very  early 
period. 

The  priests  of  Egypt  maintained  the  aqueous 
origin  of  the  globe ;  Thales  taught  that  the  solid 
materials  of  the  Earth  were  deposited  from  water ; 
Zeno  that  fire  was  the  "  prima  materia,"  and  the 
Earth  formed  from  it. 

In  the  limited  number  of  physical  subjects  that 
engaged  the  attention  of  classical  antiquity,  we  can 
include  but  a  few  insulated  phenomena  that  come 
within  the  limits  of  Geology. 

Such  striking  natural  appearances  as  earthquakes 
and  volcanos,  could  not  escape  notice,  and  we  find 
crude  theories  to  account  for  them  in  various  authors. 

The  formation  of  new  land  by  the  mud  brought 
down  and  deposited  by  rivers,  the  appearance  of 
new  islands  in  the  ocean,  and  the  encroachment  of 
the  sea,  on  the  land,  are  not  unfrequently  mentioned 
by  Pliny,  Aristotle,  and  Strabo. 

With  one  of  the  great  facts  of  geological  investi 


Jl 

1 


HISTORY  OF  GEOLOGY.  245 

gation  and  speculation  they  were  also  acquainted. 
This  fact,  is,  that  shells,  and  various  other  organic 
remains,  occur  in  immense  quantities,  embedded  in 
the  solid  rock,  and  often  at  a  great  depth  below  the 
surface ;  but  it  seems  to  have  excited  little  of  their 
attention  or  curiosity. 

It  seems  singular  that  this  fact,  which  would  have 
afforded  demonstrative  evidence  of  the  favorite  dog- 
ma of  some  of  their  schools,  that  the  face  of  nature 
was  continually  changing,  and  what  was  now  dry 
land,  was  once  covered  by  the  sea,  should  have  been 
overlooked. — 

Ovid  alone,  with  a  view  to  illustrate  the  above 
doctrine,  puts  into  the  mouth  of  Pythagoras,  the 
words, 

"  Vidi  factas  ex  asquore  terras 

"  Et  procul  a  pelago  conchae  jacuere  marinae." 

In  some  of  their  physical  notions,  we  perceive  the 
germs  of  more  modern  theories,  or  at  least,  the  theo- 
ries have  been  formed  from  an  imperfect  observa- 
tion of  similar  facts. 

The  theory  adopted  and  adorned  by  Buffon,  who 
appears  to  have  consider  the  displacement  of  the  sea 
as  a  periodical  revolution  of  nature ;  and  the  wfld 
but  splendid  conception  embraced  by  many  of  the 
ancient  schools,  and  particularly  by  the  Stoics,  that 
the  Earth  had  experienced  frequent  destructions  and 
renovations,  through  the  agency  of  igneous  and 
aqueous  devastations,  recurring  after  distant  inter- 
vals of  time,  reminds  us,  in  many  points,  of  the 
Huttonian  theory  of  the  Earth. — It  seems  more  con- 

21* 


246  HISTORY  OF  GEOLOGY. 

sistent,  however,  with  the  general  tenor  of  their  phi- 
losophical speculations,  to  believe  that  it  was  de- 
duced from  their  high  "  a  priori"  principles,  rather 
than  from  any  train  of  inductive  reasoning,  founded 
on  observation. 

Middle  Ages. 

In  the  middle  ages,  the  Arabian  writers  seem  to 
have  cultivated  mineralogy  with  some  success. 

Tenth  Century. 

Avicenna,  at  the  close  of  the  10th  century,  was 
the  first  who  laid  the  foundation  of  a  rational  ar- 
rangement of  minerals. 

Several  Italian  writers  noticed  the  appearance  of 
fossil  shells  in  their  hills  at  an  early  period. 

Fifteenth  Century. 

In  the  15th  century,  Alessandro  degli  Alessandri, 
proposed  the  hypothesis,  that  the  axis  of  the  Earth's 
rotation,  might,  originally,  have  had  a  different  po- 
sition from  the  present  one,  as  a  means  of  account, 
ing  for  the  change  in  the  land  and  sea. 

Sixteenth  Century. 

Fracastero,  in  1517  enters  at  large  into  a  discus, 
sion  of  the  land  having  been  covered  by  water,  and 
he  arrives  at  the  conclusion,  that  the  phenomena 
are  such  as  cannot  be  explained  by  a  transient  con- 
vulsion, such  as  the  deluge  alone. 

The  change  in  the  axis  of  the  Earth,  found  an 
advocate  in  more  recent  times  in  Voltaire,  who  be- 
lieved in  the  wild  tradition  of  the  Egyptians,  that 


HISTORY  OF  GEOLOGY.  247 

the  sun  had  twice  risen  in  the  west  within  the  me- 
nioiy  of  that  nation,  and  ascribed  this,  to  a  revolu- 
tion of  the  Earth's  axis  around  one  of  its  equatorial 
diameters,  which  he  imagined  was  completed  in 
4,000,000  years. 

It  is  however  needless  to  add,  that  astronomical 
observation  does  not  afford  the  slightest  ground  for 
these  speculations  ;  the  real  change  in  the  obliquity 
of  the  ecliptic  being  confined  within  very  narrow 
limits,  is  inadequate  to  account  for  any  geological 
phenomena. 

George  Agricola,  who  flourished  during  the  first 
half  of  the  16th  century,  published  on  several 
branches  of  mineralogy,  and  he  illustrated  in  a  full, 
precise,  and  clear  manner,  the  various,  phenomena 
of  metalic  veins. 

Before  the  close  of  the  16th  century,  George 
Owen,  an  Englishman,  left  behind  him  a  valuable 
manuscript  work  on  the  topography  of  his  native 
county.  In  this,  we  find  the  earliest  attempt  to 
establish  the  important  and  fundamental  geological 
fact,  that  the  same  series  of  rocks  succeed  each 
other  in  a  regular  order,  through  extensive  tracts  of 
country ;  but  his  work  having  remained  in  manu- 
script until  recently,  shows  us  a  striking  instance 
of  those  anticipations  of  subsequent  discoveries, 
which  may  be  often  observed  in  the  history  of 
science,  but  cannot  have  contributed  in  any  degree 
to  their  advancement. 

•   Seventeenth  Century. 

During  the  17th  century,  we  find  little  but  theo- 
retical writers  without  observation,  as  Burnet,  or 


248  HISTORY  OF  GEOLOGY. 

collectors  without  general  views ;  but  Llwydd,  ap- 
pears to  have  been  partially  acquainted  with  the 
fact,  that  particular  shells  occur  in  particular  strata. 

Lister,  demands  our  attention,  as  the  first  pro- 
poser of  regular  geological  maps.  The  very  idea 
of  this  proposal,  shows  an  acquaintance  with  the 
regularity  of  geological  structure,  occurring  over 
extensive  districts.  Another  important  observation 
in  relation  to  him,  is,  that  he  was,  in  at  least  one  in- 
stance,  led  to  the  distinction  of  strata,  by  their  or- 
ganic remains. 

Eighteenth  Century. 

Woodward's  essay  on  the  natural  history  of  the 
Earth  in  1702,  was  the  first  thing  published  in  Eng- 
land that  contained  any  important  geological  facts. 

The  discourses  of  Hooke  on  earthquakes  in  1705, 
the  physico  theological  discourses  of  Ray  in  1713, 
and  the  new  theory  of  the  Earth  by  Whiston  in 
1722,  were  chiefly  of  a  speculative  nature.  In 
1723  we  find  the  arrangement  of  the  strata  in  regu- 
lar zones,  described  by  Hollo  way  (Phil.  Trans.)  and 
by  Mr.  Packe  in  1730 ;  and  about  the  same  time 
Strachey,  described  the  coal  district  of  Somerset, 
shire,  and  he  observed  the  inclined  position  of  the 
coal  strata  and  the  horizontal  superincumbent  rocks* 
Strachey  was  also  acquainted  with  the  regular  suc- 
cession of  strata. 

Towards  the  middle  of  the  18th  century,  the  scat- 
tered rays  of  information  are  seen  beginning  to 
converge  into  a  stronger  and  more. steady  light, 
and  to  approximate  to  a  regular  system. 

In  1740,  DeMaillet,  who  had  long  resided  in 
Egypt,  adopted  the  opinions  of  the  ancient  philoso 


HISTORY  OF  GEOLOGY.  249 

phers,  and  having  seen  the  waters  by  their  earthy 
depositions  contribute  to  the  extension  and  forma- 
tion  of  land,  he  attempted  a  general  explanation  of 
the  formation  of  the  Earth. 

In  1746,  Guettarcl  first  executed  the  idea  pro- 
posed by  Lister  years  before,  of  geological  maps, 
but  by  attempting  too  much,  he  brought  his  method 
into  disrepute. 

Lehman  in  1756  was  the  first  to  establish  firmly 
the  great  distinctions  between  the  primitive  and  se- 
condary rocks. 

In  1760,  the  Rev.  J.  Mitchell  in  a  paper  on  the 
causes  and  phenomena  of  earthquakes,  gave  the 
whole  doctrine  of  the  regular  succession  of  the 
stratified  masses,  constituting  the  crust  of  the  Earth, 
and  he  observes  that  this  structure  is  such,  that  we 
may  always  meet  with  successive  zones  of  the  vari- 
ous mineral  masses,  lying  paralled  to,  and  rising  to- 
wards the  principal  mountain  range. 

Fuchsel,  a  German  writer,  made  known  that  cer- 
tain rocks  were  not  only  characterized  by  their 
mineralogical  structure,  but  by  their  organic  re. 
mains,  in  two  works  he  published  in  1762  arid  1772. 
He  determined  the  relative  positions  of  many  of 
the  rocks.  His  theoretical  geology  is  remarkable, 
and  far  superior  to  that  of  Werner,  which  was  after- 
wards so  generally  adopted.  See  De  La  Beche,  p. 
181. 

In  1778,  Whitehurst's  enquiry  into  the  original 

state  of  the  Earth,  although  mostly  theoretical  and 

speculative,  contained  some  good  observations  on 

the  geological  structure  of  some  parts  of  England. 

James  Douglass,  in  1785,  published  a  dissertation 


250  HISTORY  OF  GEOLOGY. 

on  the  antiquity  of  the  Earth,  in  which  some  or. 
ganic  remains  were  particularly  considered. 

In  1788,  Hutton  published  his  theory  of  the  Earth, 
and  this  is  a  work  which  has  exerted  a  lasting  in- 
fluence over  geologists.  Hutton  has  the  merit  of 
having  first  directed  the  attention  of  geologists  to 
the  important  fact  of  granite  veins  issuing  appa- 
rently from  heels  and  strata  of  granite,  and  travers- 
ing ail  the  surrounding  rocks. 

He  also  brought  forward  in  a  striking  manner, 
the  circumstances  that  seem  to  show  the  igneous 
origin  of  the  trap  rocks  ;  but  the  wildness  of  some 
of  his  theoretical  views,  may  well  go  to  counter- 
balance the  utility  of  the  facts  he  gathered  from  ob- 
servation. 

Werner  published  his  researches  in  1787,  but  his 
system  seems  to  have  received  accessions  until  1796. 
It  is  difficult  to  estimate  his  independent  and  real 
merits,  as  he  never  published  much  of  his  system ; 
we  are  informed  of  it  only  through  his  pupils.  His 
principal  merits  seem  to  have  been  in  a  superior 
acquaintance  with  the  mineralogical  characters  of 
rocks,  in  having  traced  with  minuteness  the  primi- 
tive, transition,  and  secondary  rocks,  in  that  part 
of  Germany,  and  in  reducing  the  hitherto  irregular 
elements  of  geological  science,  into  a  more  strict 
and  systematic  form.  His  theory  must  now  appear 
to  almost  all,  as  among  the  most  unphilosophical 
and  unsuccessful  yet  framed,  and  his  few  remaining 
adherents  are  one  by  one  abandoning  his  most 
characteristic  opinions. 

There  appears  to  have  been  in  the  character  of 
Werner  a  concentration  of  all  his  powers  to  the  ad- 


HISTORY    OF   GEOLOGY.  251 

vancement  of  his  favorite  pursuit,  and  his  zeal  was 
communicated  to  all  his  pupils.  "  Werner's  mind 
was  at  once  imaginative  and  richly  stored  with  mis- 
cellaneous knowledge.  He  associated  every  thing 
with  his  favourite  science  and  in  his  excursive  lect- 
ures he  pointed  out  all  the  economical  uses  of  mine- 
rals and  their  application  to  medicine  ;  the  influ- 
ence of  the  mineral  composition  of  rocks  upon  the 
soil,  and  of  the  soil  upon  the  resources,  wealth,  and 
civilization  of  man. "  The  qualities  of  certain  stones 
used  in  building,  would  lead  him  to  descant  on  the 
architecture  of  different  ages  and  nations,  and  the 
physical  geography  frequently  invited  him  to  treat  of 
military  tactics.  The  charm  of  his  manners  and  his 
eloquence,  kindled  enthusiasm  in  the  minds  of  his  pu- 
pils, many  of  whom  only  intended  at  first  to  acquire 
a  slight  knowledge  of  mineralogy  ;  but  when  they 
had  once  heard  him,  devoted  themselves  to  it  as  the 
business  of  their  lives.  In  a  few  years  a  small  school 
of  mines,  before  unheard  of  in  Europe,  was  raised,  to 
the  rank  of  a  great  university,  and  men  already 
distinguished  in  science  studied  the  German  lan- 
guage, and  came  from  the  most  distant  countries  to 
hear  the  great  oracle  of  Geology." — [Cuvier,  Eloge 
de  Werner,  and  LyeWs  Principles  of  Geology.  Vol. 
I.  p.  64.] 

Werner,  has,  by  his  popularity,  and  the  spirit  of 
enquiry  he  set  on  foot,  probably  done  more  for  the 
advancement  of  Geology,  than  any  other  individual, 
and  he  has,  perhaps,  properly,  been  called,  the  Father 
of  the  science. 

The  travels  of  Saussure  in  the  Alps,  afforded  im- 
portant contributions  of  geological  science,  and  Pal- 


£52  HISTORY    OF    GEOLOGY. 

las,  in  his  mineralogical  surveys  of  the  Russian  Em 
jure,  has  noted  many  important  geological  facts. 

In  1790,  Mr.  Wm.  Smith,  a  mining  engineer, 
commenced  his  geological  researches,  and  in  a  few 
years  published  local  maps  of  a  considerable  por- 
tion of  England.  His  labours  have  done  more  to 
advance  this  science  in  England,  than  those  of  any 
other  individual,  and  by  many  he  is  supposed  to 
have  done  as  much  for  it  as  Werner. 

Since  the  commencement  of  the  19th.  century, 
more  materials  have  been  collected  to  forward  the 
science  of  geology  than  had  been  before.  A  nu- 
merous and  ablest  class  of  geologists  have  arisen 
since  that  time  in  England,  and  another  in  France, 
and  the  United  States  have  produced  some.  The 
principal  of  the  English  Geologists  are,  Buckland, 
De  La  Beche,  Conybeare,  Phillips,  Murchinson, 
Lyell,  Grenouch,  Bakewell,  Parkinson,  Webster, 
Sedgewick,  McCulloch,  Taylor,  Fox,  Stokes,  Fit- 
ton,  and  Warburton. 

Among  the  French  geologist  who  have  done 
most,  may  be  mentioned  Cuvier,  the  Brongniarts, 
(father  and  son,)  Boue,  De  Luc,  Saussure,  and  Elei 
de  Beaumont. 

In  Germany,  De  Buch,  Raumer,  Ebel,  Keferstein, 
Brown,  and  many  others  might  be  mentioned  in 
various  parts  of  Europe.  In  the  United  States, 
Maclure,  Silliman,  Bruce,  Mitchell,  Hitchcock, 
Morton,  Eaton,  James,  Hayden,  Olmstead,  Gleav- 
!and,  Webster,  Cist,  Hildreth,  Beck,  Torrey,  Eights, 
Pierce,  Dekay,  Cooper,  Cozzens,  Vanuxem,  Con- 
rad, Emmons,  Troost,  Featherstonhaugh,  Taylor, 
Houghton,  Owen,  the  Rodgers,  Booth,  and  many 


HISTORY    OF    GEOLOGY.  253 

others  have  been,  and  some  of  them  are  still,  engag- 
ed in  developing  the  geology  of  our  territory. 

Mr.  Maclure  and  Gen.  S.  Van  Rensselaer,  deserve 
notice  particularly  ;  the  first  for  his  great  geological 
survey  of  the  United  States,  and  his  munificent  do- 
nations to  the  various  scientific  societies,  of  rare 
arid  valuable  books  ;  the  other  for  his  liberality  in 
causing  a  geological  survey  to  be  made  at  his  ex- 
pense. These  two  men  have  given  an  impulse  to  the 
science,  that  must  result  in  the  developement  of  the 
geology  and  resources  of  this  country. 

Before  geology  ranked  as  a  science,  the  efforts  of 
the  early  speculators  were  directed  to  the  wild  and 
ample  region  of  pure  theory,  connected  with  the 
origin  of  the  globe  ;  the  connection  of  scriptural 
history  with  physical  events,  and  the  traces  and  ef- 
fects of  the  Noachian  deluge. 

The  descriptive  part  of  geology  was  then  a  blank. 
— For  their  soaring  views,  it  would  have  appeared 
beneath  the  dignity  of  science  to  classify  rocks  and 
minerals,  or  descend  into  a  minute  comparison  of 
the  organic  remains  entombed  in  the  rocky  strata, 
with  the  existing  species. — Why  should  they?sto 
whom  nature  had  revealed  her  ample  page,  scruti- 
nize the  "  modus  operandi,"  which,  they  imagined 
would  add  little  to  a  knowledge  of  general  facts  or 
laws  ?  Why  should  the  phenomena  of  active  caus- 
es be  minutely  examined,  the  destructive  influence 
of  volcanos  and  earthquakes,  or  the  devastating 
operations  of  seas,  and  rivers,  and  torrents,  when  a 
comet  might  so  easily  in  imagination  be  summoned 
to  scorch  the  Earth  from  pole  to  pole,  and  by  its 
attraction  submerge  the  continents  and  change  the 
22 


254  HISTORY    OF    GEOLOGY. 

axis.  No  dynamical  effect  was  too  great  for  such 
resources. — As  new  phenomena  arose,  new  under- 
plots were  added  to  the  drama  of  creation,  and  so 
remained  until  by  new  discoveries,  new  substitutions 
were  rendered  necessary.  An  advancing  state  of 
physical  science,  led  men  to  correct  the  laxity 
which  the  theories  of  the  formation  of  the  Earth 
had  assumed,  in  the  time  of  Burnet  and  Whiston. 
Werner  and  Hutton,  both  of  whom  gave  much 
weight  to  the  fact  of  observation,  raised  a  new 
and  very  superior  class  of  geologists.  Whatever 
may  have  been  the  errors  of  their  theories,  it  ia 
certain  that  their  influence  on  the  minds  of  men 
has  been  of  much  importance  in  causing  the  ad- 
vance  of  the  science.  Button's  doctrine  of  the 
consolidation  of  earthy  materials  by  heat  and  pres- 
sure, and  Werner's  theory  of  universal  formations, 
were  brought  to  the  tests  of  experiment  and  obser- 
vation. The  one  was  confirmed  more  satisfactorily 
than  could  have  been  expected  under  facitious  cir- 
cumstances ;  the  other  was  shown  to  have  origina- 
ted in  its  utmost  generality  in  the  narrow  views 
of  its  ingenious  but  untra veiled  author.  One  was 
passed  by  in  silent  neglect,  the  other  attracted 
crowds  of  disciples  from  all  parts  of  Europe.  The 
former  of  these  men  died  when  his  theory  had 
hardly  attracted  notice,  the  latter,  in  the  full  career 
of  glory.  Like  the  fabled  Phenix,  Button's  theory 
arose  from  his  ashes,  but  from  the  time  Werner 
was  laid  in  his  grave,  his  was  found  wanting  in  the 
generality  which  he  had  assigned  it. 

The  acrimony,  which  the  controversy  between 
the  disciples  of  these  two  men  produced,  caused  a 


HISTORY    OF    GEOLOGY.  255 

reaction,  and  geologists  resolved  for  a  time  to  ban- 
ish hypotheses,  and,  unbaissed  by  theory,  endeavour 
to  view  nature  as  she  is  ;  and  thus,  men  have  be- 
come habituated  to  using  well  their  hands  and  eyes, 
and  amassing  facts  before  theorizing. 

The  practical  utility  of  the  applications  of  geol- 
ogy in  agriculture,  rninery,  and  engineering,  and 
developing  the  latent  resources  of  the  country,  is 
now  so  well  understood,  that  more  than  half  of  the 
States  of  the  Union,  are  having  geological  surveys 
made  of  their  territories,  and  the  others  must,  un- 
doubtedly, ere  long,  follow  in  the  train.  Our  youth 
in  common  schools  and  academies,  may  be  made  a 
more  powerful  engine  to  develope  the  resources  of 
our  country,  than  all  the  geologists  in  the  world 
unaided.  We  wish  our  youth  to  be  instructed  in 
the  elements  of  geology,  and  to  become  familiar 
with  the  common  useful  minerals  and  rocks.  Could 
we  accomplish  this,  we  would  soon  have  three  mil- 
lions of  pairs  of  eyes  engaged  in  observing  the  re- 
sources of  our  country  instead  of  a  few  dozens. 
Then,  by  means  of  experienced  geologists,  we  might 
hope  to  be  able  to  combine  and  generalize  the  mul- 
titudes of  observations,  and  soon  develope  the  fa 
sources  of  our  country ;  and  thus  give  a  new  im- 
pulse to  every  branch  of  industry,  while  new  fields 
of  enterprise  would  be  opened  for  the  multitudes 
which  are  yet  to  people  our  extended  territory. 


GLOSSARY 

OF  SOME 

GEOLOGICAL  TERMS, 

FROM 

LYELL'S  GEOLOGY  AND  OTHER  SOURCES. 


Alluvial.     The  adjective  of  Alluvium. 

Alluvion.     A  synonim  of  Alluvium. 

Alluvium.  Recent  deposits  of  earth,  sand,  gravel,  mud, 
stones,  peat,  shell  banks,  shell  marl,  drift  sand,  &c.,  result- 
ing  from  causes  now  in  action.  This  term  is  generally  ap- 
plied to  those  deposits  in  which  water  is  the  principal  agent. 

Alum  rocks.     Rocks  which,  by  decomposition,  form  Alum. 

Amorphous.     Bodies  devoid  of  regular  form. 

Amygdaloid.  A  trap  rock  which  is  porous  and  spongy, 
with  rounded  cavities  scattered  through  its  mass.  Agates 
and  simple  minerals  are  often  contained  in  these  cavities. 

Anthracite.  A  species  of  mineral  coal,  hard,  shining, 
black,  and  devoid  of  bitumen.  • 

Anticlinal.  An  anticlinal  ridge  or  axis  is  where  the  strata 
along  a  line  dip  contrariwise,  like  the  sides  of  the  roof  of  a 
house. 

Arenaceous.     Sandy. 

Argillaceous.     Clayey. 

Augite.  A  simple  mineral  of  variable  colour,  from  black 
through  green  and  gray  to  white.  It  is  a  constituent  of 
many  volcanic  and  trappean  rocks,  and  is  also  found  in  some 
of  the  granitic  rocks. 

Avalanche.  This  term  is  usually  applied  to  masses  of  ice 
and  snow  which  have  slidden  from  the  summits  or  sides  of 
22* 


258 


GLOSSARY. 


mountains.  It  is  now  also  applied  to  slides  of  earth  and 
elay. 

Basalt.  One  of  the  common  trap  rocks.  It  is  composed 
of  Augite  and  feldspar,  is  hard,  compact,  and  dark  green  or 
black,  and  has  often  a  regular  columnar  form.  The  palisades 
of  the  Hudson  show  the  columnar  aspect  of  trap  rocks.  The 
Giants'  causeway  is  cited  as  an  example  of  Basaltic  rocks, 
and  the  columnar  structure  is  there  very  strikingly  displayed. 

Bitumen.  Mineral  pitch,  which  is  often  seen  to  ooze  from 
fossil  coal  when  on  fire. 

Bituminous  Shale.  A  slaty  rock,  containing  bitumen, 
and  which  occurs  in  the  coal  measures. 

Blende.     Sulphuret  of  Zinc.     A  common  shining  zinc  ore. 

Bluffs.  High  banks  of  earth  or  rock  with  a  steep  front. 
The  term  is  generally  applied  to  high  banks  forming  the 
boundaries  of  a  river,  or  river  alluvions. 

Botryoidal.     Resembling  a  bunch  of  grapes  in  form. 

Boulders.  Rocks  which  have  been  transported  from  a  dis- 
tance, and  more  or  less  rounded  by  attrition  or  the  action  of 
the  weather.  They  lie  upon  the  surface  or  loose  in  the  soil, 
and  generally  differ  from  the  underlying  rock  in  the  neigh, 
borhood. 

Breccia.  A  rock  composed  of  angular  fragments  cement- 
ed together  by  lime  or  other  substances. 

Calc  Sinter.  A  German  term  for  depositions  of  limestone 
from  springs,  and  waters  which  contain  this  mineral  in  solu- 
tion. 

Calcareous  rocks.     A  term  synonimous  with  limestones. 

Calcareous  Spar.     Crystallized  carbonate  of  lime. 

Carbon.     The  combustible  element  of  coal. 

Carbonates.  Chemical  compounds  containing  carbonic 
acid,  which  is  composed  of  oxygen  and  carbon. 

Carbonic  Acid.  An  acid  gaseous  compound,  incapable  of 
supporting  combustion,  and  deleterious  to  animal  life.  It  is 
common  in  caves  and  wells,  and  many  incautious  persons 
loose  their  lives  in  consequence  of  descending,  without  first 
ascertaining  its  presence  by  letting  down  a  lighted  candle. 
Man  cannot  live  where  a  candle  will  not  burn  freely. 

Carboniferous.  Coal  bearing  rocks.  This  term  has  been 
applied  to  a  formation  belonging  to  an  ancient  group  of  secon- 


GLOSSARY,  259 

dary  rocks  which  contains  coal.  The  term  is  now  used  in  a 
more  enlarged  sense,  and  may  be  applied  to  any  rocks  con- 
taining coal. 

Chert.  A  siliceous  mineral,  approaching  to  chalcedony, 
flint  and  hornstone.  It  is  usually  found  in  limestone. 

Chlorite.     A  soft  green  scaly  mineral,  slightly  unctuous. 

Chloritic  Slate.     Slate  containing  chlorite. 

Clinkstone.  A  slaty  feldspathic  or  basaltic  rock,  which  is 
sonorous  when  struck. 

Cleavage.  The  separation  of  the  laminoe  of  rocks  and  min. 
erals  in  certain  constant  directions.  They  are  not  always 
parallel  to  the  planes  of  stratification,  but  are  often  mistaken 
for  them. 

Coal  formation.  Coal  measures.  These  terms  are  con. 
sidered  synonimous,  and  refer  to  the  great  deposit  of  coal  in 
the  older  secondary  rocks,  which  has  been  called  the  "  inde- 
pendent coal  formation."  There  are,  however,  deposits  of 
carbonaceous  matter  in  all  the  geological  periods,  and  several 
of  them  might  also  be  called  coal  formations. 

Conformable.  When  strata  are  arranged  parallel  to  each 
other,  like  the  leaves  of  a  book,  they  are  said  to  be  conforma. 
ble.  Other  strata  lying  across  the  edges  of  these  may  be  con- 
formable among  themselves,  but  unconformable  to  the  first 
set  of  strata. 

Conglomerate,  or  Puddingstone.  Rocks  composed  of  round, 
ed  masses,  pebbles  and  gravel  cemented  together  by  a  silice- 
ous, calcareous,  or  argillaceous  cement. 

Cretaceous.     Belonging  to  the  Chalk  formation. 

Crop  out  and  out  crop.  Terms  employed  by  Geologists 
and  Mining  Engineers,  to  express  the  emergence  of  rock,  in 
place,  on  the  surface  of  the  earth  at  the  locality  where  it  is 
said  to  crop  out. 

Crystalline.  An  assemblage  of  imperfectly  defined  cry. 
stals,  like  loaf  sugar  and  common  white  marble. 

Delta.     Alluvial  land  formed  at  the  mouths  of  rivers. 

Denudation.  A  term  used  to  express  the  bare  state  of  the 
rocks  over  which  currents  of  water  have  formerly  swept,  and 
laid  the  rocks  bare,  or  excavated  them  to  form  valleys  of  de- 
nudation. 

Deoxidize.     To  separate  oxygen  from  a  body. 


260  GLOSSARY. 

Dykes.  A  kind  of  vein  intersecting  the  strata,  and  usually 
filled  with  some  unstratified  igneous  rock,  such  as  granite, 
trap  or  lava.  These  materials  are  supposed  to  have  been  in- 
jected in  a  melted  state  into  great  rents  or  fissures  in  the 
rocks. 

Diluvium  and  Diluvion.  Deposits  of  boulders,  pebbles, 
and  gravel  which  many  geologists  have  supposed  were  pro- 
duced  by  a  diluvial  wave  or  deluge  sweeping  over  the  surface 
of  the  earth. 

Dip.  Where  strata  are  not  horizontal,  the  direction  in 
which  their  planes  sink  or  plunge,  is  called  the  direction  of 
the  dip,  and  the  angle  of  inclination,  the  angle  of  dip. 

Dolomite.  A  magnesian  limestone  belonging  to  the  pri- 
mary class.  It  is  usually  granular  in  its  structure,  and  of  a 
friable  texture. 

Dunes.     Sand  raised  into  hills  and  drifts  by  the  wind. 

Earth's  Crust.  The  superficial  parts  of  our  planet  which 
are  accessible  to  human  observation. 

Eocene.  The  strata  deposited  during  the  oldest  of  the  ter- 
tiary epochs,  as,  for  example,  the  Paris  Basin. 

Estuaries.  Inlets  of  the  sea  into  the  land.  The  tides  and 
fresh  water  streams  mingle  and  flow  into  them.  They  in- 
clude not  only  the  portion  of  the  sea  adjacent  to  the  mouths 
of  rivers,  but  extend  to  the  limit  of  tide  water  on  these  streams. 

Exuvia.     In  Geology,  fossil  remains. 

Fault.  A  dislocation  of  strata,  at  which  the  layers  on  one 
side  of  a  dyke  or  fissure  have  slidden  past  the  corresponding 
ones  on  the  other.  These  dislocations  are  often  accompanied 
by  a  dyke.  They  vary  from  a  few  lines  to  several  hundred 
feet. 

Feldspar.  One  of  the  simple  minerals,  and,  next  to  quartz, 
one  of  the  most  abundant  in  nature. 

Ferruginous.     Containing  iron. 

Fluviatile.     Belonging  to  a  river. 

Formation.  A  group  of  rocks  which  were  formed  during 
a  particular  period,  or  which  are  referred  to  a  common  origin. 

Fossils.  The  remains  of  animals  and  plants  found  buried 
in  the  earth,  or  enclosed  in  rocks.  Some  of  these  are  but 
slightly  changed,  others  are  petrified  and  the  organic  replaced 
by  mineral  matter ;  some  have  decayed  and  left  the  impres- 


GLOSSARY  261 

sion  of  the  bodies,  while  others  have  been  formed  by  mineral 
matter  deposited  in  the  cavities  left  by  the  decay  of  the  or- 
ganic  body.  These  last  are  called  casts.  The  term  petrifac- 
tion is  applied  to  those  cases  in  which  organic  matter  has 
been  replaced  by  mineral  substances.  The  form  and  struc- 
ture of  the  original  body  both  remain.  In  casts  the  exterior 
form  alone  is  preserved.  Fossils  are  also  called  organic  re- 
mains. 

Fossiliferous.     Containing  organic  remains. 

Galena.     An  ore  of  lead  composed  of  lead  and  sulphur. 

Garnet.  A  simple  mineral,  which  is  usually  red  and  crys- 
tallised. It  is  abundant  in  most  primitive  rocks. 

Gneiss.  A  stratified  primary  rock,  composed  of  the  same 
materials  as  granite,  but  the  mica  is  distributed  in  parallel 
layers,  which  give  it  a  striped  aspect. 

Geology.  A  science  which  has  for  its  object  to  investigate 
the  structure  of  the  earth,  the  materials  of  which  it  is  com- 
posed, the  manner  in  which  these  are  arranged,  with  regard 
to  each  other ;  and  it  considers  the  action  of  all  natural  causes 
in  producing  changes,  such  as  the  effects  of  frost,  rain,  floods, 
tides,  currents,  winds,  earthquakes  and  volcanos. 

Economical  Geology  refers  to  the  applications  of  geological 
facts  and  observations  to  the  useful  purposes  of  civilized  life. 

Granite.  An  unstratified  rock,  composed  generally  of 
quartz,  feldspar  and  mica,  and  it  is  usually  associated  with 
the  oldest  of  the  stratified  rocks. 

Graywacke  Grauwacke.  A  group  of  strata  in  the  transi. 
tion  of  rocks ;  but  the  term  has  been  so  indefinitely  applied, 
that  other  names  will  probably  be  substituted.  • 

Greenstone.  A  trap  rock,  composed  of  hornblend  and  feld. 
spar, 

Grit.     A  coarse-grained  sandstone. 

Gypsum.  A  mineral,  composed  of  sulphuric  acid  and 
lime,  and  extensively  used  as  a  stimulant  manure,  and  for 
making  stucco  and  plaster  casts,  &c.  It  is  also  called  Plas. 
ter  of  Paris. 

Hornblende.  A  mineral  of  a  dark  green  or  black  colour, 
and  which  is  a  constituent  part  of  greenstone. 

Hornstone.  A  siliceous  mineral,  approaching  to  flint  in 
its  characters. 


262  GLOSSARY. 

In  Situ,  In  their  original  position  where  they  were 
formed. 

Laminae.  The  thin  layers  into  which  strata  are  divided, 
but  to  wiiich  they  are  not  always  parallel. 

Lacustrine.  Belonging  to  a  lake.  Depositions  formed  in 
ancient  as  well  as  modern  lakes,  are  called  lacustrine  deposits. 

Landslip.  It  is  the  removal  of  a  portion  of  land  down  an 
inclined  surface.  It  is  in  consequence  of  the  presence  of 
water  beneath,  which  either  washes  away  the  support  of  the 
superincumbent  mass,  or  so  saturates  the  materials  that  they 
become  a  slippery  paste. 

Line  of  Bearing,  is  the  direction  of  the  intersection  of  the 
planes  of  the  strata  with  the  plane  of  the  horizon. 

Lignite.  Wood  naturally  carbonized  and  converted  into  a 
kind  of  coal  in  the  earth. 

Littoral.     Belonging  to  the  shore. 

Loam.     A  mixture  of  sand  and  clay. 

Mural  Escarpment.  A  Rocky  cliff  with  a  face  nearly  ver- 
tical like  a  wall. 

Mammillary.  A  surface  studded  with  smooth  small  seg- 
ments of  spheres  like  the  swell  of  the  breasts. 

Mammoth.     An  extinct  species  of  the  elephant. 

Marl.  By  this  term  an  argillaceous  carbonate  of  lime  is 
usually  implied.  By  custom,  its  signification  is  much  more 
extended,  and  means  mineral  substances,  which  act  as  stimu- 
lating or  fertilizing  manures.  There  are  clay  marls,  shell 
marls,  and  various  others. 

Mastodon.  A  genus  of  extinct  fossil  animals  allied  to  the 
elephant.  They  are  so  called  from  the  form  of  the  grinders 
which  have  their  surfaces  covered  with  conical  mammillary 
crests. 

Matrix.  The  mineral  mass  in  which  a  simple  mineral  is 
imbeded,  is  called  its  matric  or  gangue. 

Megatherium.  A  fossil  extinct ;  quadruped  resembling  a 
gigantic  sloth. 

Mechanical  origin  Rocks  of,  Rocks  composed  of  sand,  peb- 
bles or  fragments,  are  so  called,  to  distinguish  them  from 
those  of  a  uniform  crystalline  texture,  which  are  of  chemical 
origin. 

Mica.     A  simple  mineral  having  a  shining  silvery  surface, 


GLOSSARY.  263 

and  capable  of  being  split  into  very  thin  elastic  leaves  or 
scales.  The  brilliant  scales  in  granite  and  gneiss  are  mica. 

Mica  Slate.  One  of  the  stratified  rocks  belonging  to  the 
primary  class.  It  is  generally  fissile,  and  is  characterized  by 
being  composed  of  mica  and  quartz,  of  which  tho  former 
either  predominates,  or  is  disposed  in  layers,  so  that  its  flat 
surfaces  give  it  the  appearance  of  predominating. 

Miocene.  Oae  of  the  deposits  of  the  tertiary  epoch.  It  is 
more  recent  than  the  eocene,  and  older  than  the  plwcene. 

Mollusca.  Molluscous  animals.  "  Animals,  such  as  shell 
fish,  which,  being  devoid  of  bones,  have  soft  bodies." 

Mountain  Limestone.  "  A  series  of  limestone  strata,  of 
which  the  geological  position  is  immediately  below  the  coal 
measures,  and  witli  which  they  also  sometimes  alternate." 

Muriate  of  Soda.     Common  Salt. 

Naphtha.  A  fluid  volatile  inflammable  mineral,  which  is 
common  in  volcanic  districts,  and  in  the  vicinity  of  the  Salt 
Springs  of  the  United  States. 

New  Red  Sand-stone.  "  A  series  of  sandy  and  argillaceous, 
and  often  calcareous  strata,  the  prevailing  colour  of  which  is 
brick  red,  but  containing  portions  which  are  greenish  grey. 
These  occur  often  in  spots  and  stripes,  so  that  the  series  has 
sometimes  been  called,  the  variegated  sandstone.  The  Euro- 
pean,  so  called,  lies  in  a  geological  position  immediately  above 
the  coal  measures." 

Nodule.     A  rounded,  irregular  shaped  lump  or  mass. 

Old  Red  Sand-stone.  "  A  stratified  rock,  belonging  to 
the  carboniferous  group  of  Europe." 

Oolite.  "  A  lime-stone,  so  named,  because  it  is  composed 
of  rounded  particles  like  the  roe  or  eggs  of  fish.  The  name 
is  also  applied  to  a  large  group  of  strata  characterized  by  pe- 
culiar fossils." 

Organic  Remains.     Se )  Fossils. 

Orthoceratite.  The  remains  of  an  extinct  genus  of  mol- 
luscous animals,  called  Cephalopoda.  The  orthoceratites  are 
long,  straight,  conical  chambered  shells. 

Out-crop.     See  Crop-out. 

Out-liers.  Hills  or  ranges  of  rock  strata,  occurring  at 
some  distance  from  the  general  mass  of  the  formations  to 
which  they  belong.  Many  of  these  have  been  caused  by  do* 


264  GLOSSARY. 

nudation,  having  removed  parts  of  the  strata  which  once  con. 
nectcd  the  out-liers  with  the  main  mass  of  the  formation. 

Oxide.  A  combination  of  oxygen  with  another  body.  The 
term  is  usually  limited  to  such  combinations  as  do  not  present 
active  acid  or  alkiline  properties. 

Palaeontology.     A  science  which  treats  of  fossil  remains. 

Pisolite.  A  calcareous  mineral,  composed  of  rounded  con- 
cretions  like  peas. 

Pliocene.  The  upper,  or  more  recent  tertiary  strata.  This 
group  of  strata  is  divided  into  the  older  and  newer  pliocene 
rocks. 

Petroleum.  A  liquid  mineral  pitch.  It  is  common  in  the 
region  of  salt  springs  in  the  United  States. 

Porphyry.  A  term  applied  to  every  species  of  unstratified 
rock,  in  which  detached  crystals  of  feldspar  are  diffused 
through  a  compact  base  of  other  mineral  composition. 

Productus.     An  extinct  genus  of  fossil  bivalve  shells. 

Plastic  Clay.  One  of  the  beds  of  the  Eocene  period.  The 
plastic  clay  formation  is  mostly  composed  of  sands  with  asso- 
ciate beds  of  clay. 

Pudding  Stone.     See  Conglomerate. 

Pyrites.  A  mineral,  composed  of  sulphur  and  iron.  It  is 
usually  of  a  brass  yellow,  brilliant,  often  crystallized  and  fre- 
quently mistaken  for  gold. 

Quartz.  A  simple  mineral,  composed  of  silex.  Rock 
crystal  is  an  example  of  this  mineral. 

Rock.  All  mineral  beds,  whether  of  sand,  clay,  or  firmly 
aggregated  masses,  are  called  rocks. 

Sand-stone.  A  rock  composed  of  aggregated  grains  of 
sand. 

Saurians.    Animals  belonging  to  the  lizard  tribe. 

Schist.     Slate. 

Seams.  "Thin  layers  which  separate  strata  of  greater 
magnitude." 

Secondary  Strata.  "  An  extensive  series  of  the  stratified 
rocks,  which  compose  the  crust  of  the  globe,  with  certain 
characters  in  common,  which  distinguish  them  from  another 
series  below  them,  called  primary,  and  another  above  them, 
called  tertiary." 

Sedimentary  Rocks — Are  those  which  have  been  formed 


GLOSSARY.  265 

6y  their  materials  having  been  thrown  down  from  a  state  of 
suspension  or  solution  in  water. 

Selenite.     Crystalized  gypsum. 

Septaria.  Flattened  balls  of  stone,  which  have  been  more 
or  less  cracked  in  different  directions,  and  cemented  together 
by  mineral  matter  which  fills  the  fissures. 

Serpentine.  A  rock  composed  principally  of  hydrated  sili- 
cate of  magnesia.  It  is  generally  an  unstratified  rock. 

Shale.     An  indurated  slaty  clay,  which  is  very  fissile. 

Shell  Marl — Fresh  water  Shell  Marl.  A  deposit  of  fresh 
water  shells,  which  have  disintegrated  into  a  grey  or  white 
.  pulverulent  mass. 

Shingle.  The  loose,  water-worn  gravel  and  pebbles  on 
shores  and  coasts. 

Silex.  The  name  of  one  of  the  pure  earths  which  is  the 
base  of  flint,  quartz,  and  most  sands  and  sand-stones. 

Silt.  "  The  more  comminuted  sand,  clay  and  earth,  which 
is  transported  by  running  water." 

Simple  Minerals — Are  composed  of  a  single  mineral  sub- 
stance. Rocks  are  generally  aggregates  of  several  simple 
minerals  cemented  together. 

Slate.     A  rock  dividing  into  thin  layers. 

Stalactite.  Concreted  carbonate  of  lime,  hanging  from  the 
roofs  of  caves,  and  like  icicles  in  form. 

Stalagmites.  Crusts  and  irregular  shaped  masses  of  con- 
creted carbonate  of  lime,  formed  on  the  floors  of  caves,  by 
deposits  from  the  dripping  of  water. 

Stratification.     An  arrangement  of  rocks  in  strata. 

Strata.     Layers  of  rock  parallel  to  each  other.  • 

Stratum.     A  layer  of  rocks  ;  one  of  the  strata. 

Strike.  The  direction  in  which  the  edges  of  strata  crop 
out.  It  is  synonimous  with  line  of  bearing. 

Syenite  and  Sienite.  A  granite  rock,  in  which  hornblende 
replaces  the  mica. 

Synclinal  line  and  Synclinal  axis.  When  the  strata  dip 
downward  in  opposite  directions,  like  the  sides  of  a  gutter. 

Talus.  In  geology,  a  sloping  heap  of  broken  rocks  and 
stones  at  the  foot  of  many  cliffs. 

Tertiary  Strata.  "  A  series  of  sedimentary  rocks,  with 
characters  which  distinguish  them  from  two  other  great  series 
23 


266  GLOSSARY. 

of  strata — the  secondary  and  primary — which  lie  beneath 
them." 

Testacea.  "  Molluscous  animals,  having  a  shelly  cover- 
ing." 

Tepid.    Warm. 

Thermal.     Hot. 

Thin  out.  Strata  which  diminish  in  thickness  until  they 
disappear,  are  said  to  thin  out. 

Trap — Trappean  Rocks.  Ancient  volcanic  rocks,  com- 
posed  of  feldspar,  hornblende  and  augite.  Basalt,  greenstone, 
amygdaloid  and  dolerite,  are  trap  rocks. 

Travertin.  "  A  concretionary  lime-stone,  hard  and  semi- 
crystalline,  deposited  from  the  water  of  springs." 

Tufa  Calcareous.  "  A  porous  rock,  deposited  by  calca- 
reous waters  on  exposure  to  air,  and  usually  containing  por- 
tions of  plants  and  other  organic  substances  incrusted  with 
carbonate  of  lime." 

Tufaceous.     A  texture  of  rock  like  that  of  tuff. 

Tuff  or  Tufa.  "An  Italian  name  for  a  volcanic  rock  oi 
an  earthy  texture." 

Unconformable.     See  conformable. 

Veins.  Cracks  and  fissures  in  rocks  filled  with  stony  or 
metallic  matter.  Most  of  the  ores  are  abtained  from  metal- 
lic veins. 

Zoophytes.  Coral  sponges  and  other  aquatic  animals  allied 
to  them. 


INDEX. 


A. 

Acicular  crystals, 
Acid,  definition  of, 

carbonic, 

sulphuric,  . 

sulphurous,  • 

JElna,  Mount, 

lava  of  a  single  eruption, 

once  submarine, 

volcanic  sand  of, 
Air, 
Agate, 
Agricola, 
Agriculture, 
Alcyonia, 

Alessandro  degli  Alessandri, 
Alluvion, 
Antimony, 
Arsenic, 

Atmosphere,  ~,  .        "  •  • 

Amber,  ,  #  . .. 

Amygdaloid,         "  ,  *  . 

Anthracite,  "  •;  ..  V 

Antioch  destroyed,  ,  , 

Aristotle,  '     „        '  „•    * 

Argillaceous  odour,  ^ 

"  slate, 

Augite, 
Avicemva, 
Axis  of  the  earth,  change  of, 


66 

49 

50 

49 

49 

188 

183 

190 

183 

49 

52 

247 

213 

124 

246 

87, 

149,  217 

57 

•56 

55 

113 

163 

113 

176 

244 

72 

98 

66 

246 

19,247 

268  INDEX 

B. 

Bakewcll,  .....         252 

Barium,         .....  W'lS 

Basalt,           .....  163,164 

columnar,         ....  164,  169 

artificial  formation  of,  .  '  •••; 

globular, 

tabular,  .....         J*} 

used  for  making  glass  bottles,  .  .  Io4 

Basin,  chalk,  .  •  •  .;:f  l*» 

Beaches  ancient,  .  •  •  •  ~^ 

Beds,  definition  of,  .  •  •-'•..,  •  •  \' 

Biggsby,  .  •  ^  <•  27,154 

Big  bone  lick,  .  ,  >,  •  •  Jg 

Birds,  fossil,  .  •  •  130>1?a 

Bismuth,  •  •  •  •  '  inft 
Bituminous  coal,  . 

«                  sVialp  •               **• 

snaie,  t    • 

Black  coal,  .....         1^° 

"        lead'                      '                  '                 '            $•'"  '            14« 

Bones  of  animals  in  diluvial  gravel,         ^    .    -  •         14- 

««        land  animals,                     .             •  •         jjj 
««        animals  gnawed,           _.    •    ,    ^^is 

man,                       .        ,    •        |  »    ,  •           g 

««        saurian  animals,                 .             •  -.  •  ,.        "~ 

Bone  caves  and  Breccias,              "V           *  *  \.  * 

_.  5b 

Boron,                     >    •         k     •'       ,  .   *  •-  iqQ 


Bromine,  ,     •  »  .' 

Brongniarts,          ,•-,-• 
Buckland,  .    .        r     .    . 

BufTon,  ,     •   .          • 

Building  stones,  how  to  select, 
Burnett,  ,    V        r    *  . 


Cadmium, 


INDEX.  269 

Calcareous  spar,  ....          69 

Calcium,  .  .  .  48,49 

Caloric,  definition  of,  .  .  .  .19 

Canals,  234 

Caraccas,  .....         177 

Carbon,  ..... 

Carbonate  of  lime,  ....          69 

Carbonic  acid,  .  .  .  .50 

Cardona,  salt  mountain,  .  .  .         117 

Caves,  bone,  ....         145 

Caverns  in  mountain  limestone,       .  .  .102 

Cement,  hydraulic,  ....         122 

Cerium,  .....  59 

Chalk,  formation,  ....         126 

Chalmers  on  geology,  ....  39 

Chili,  coast  of  raised,  *  176 

Chlorine,  .  .  .  .  .51 

Chlorite,  .  .  .  .  •        '  .  67 

Chloritic  granite,  .  .  .  .91 

"        slate,         .....  95 

Chrome  iron,  .  .  ...  .  71 

"         yellow,  .... 

Chromium,  .  •  .  .57 

Cist,  252 

Classification  of  rocks,         .... 

"          of  Conybeare  and  Phillips,  .  88 

"         of  De  La  Beche, 

Clay,  composition  of,  ...  62 

"     description  of,  .  .  .  Jl 

"     iron  stone,  .  .  .  .105 

"     slate,  .....          98 

Cleaveland,  .....        252 

Clinkstone,  ....  163,  164 

Coal, 112 

*  anthracite,         ..... 

*  bituminous,                     .             .             .             .112 
«    caking,               .....         112 
«    charcoal,            .....  52 
«    field,                  ....             108,109 
"  origin  of, 109 

23* 


270  INDEX. 

Coal  measures,          .....         105 

mines,                 .             .  .  .  .         109 

"      explosion  of,  .  .  .178 

of  Pennsylvania,            .  .  .  .112 

searching  for,                 .  .  .  .111 

sea,  112 

Tioga,                        £ :..  ..  .  .  .         112 

Virginia,                       .-  „•*  .  .  .         11% 

Cobalt,          .            .        ;.;„''•/  ...  58 

Coccolite,              ;:'-  .             • '-  .*  .  .  *           66 

Columbium,               •             .  .  .  .57 

Columnar  structure,              ,f  .  .  .         166 

trap,         .          :;»  V-  .  .         169 

Combination  of  bodies,         .  «  .  4& 

Compact,  definition  of,  *'    .  V  .  .           1? 

feldspar,                 .-  %-  '  .  .           92 

"         limestone,             .  ,  .  '  "~ /'  .         121 

Conglomerate,           .             .  .  L  .  .         116 

Contorted  rocks,                     .  .  .  .95 

"        stratification,  '  .    .  r™  77,  80 

Conybeare,                .          '•;  Y  "  .  .'  -"  .         252 

Copper,                      »  '  (     •  » .  •  •  .           59 

Coral  rocks,              .        |    »  •    .  f .:-.-.*  124,  15!* 

Cornelian,                  »        '     «  •  .  •  . '""       5S 
Crust  of  the  globe, 

"     comparison  with  the  mass  of  the  globe,  .  ./      22 

Crater  of  volcanos,           ••'-«'.•.,  .  .  •  .      180 

Crystal,                       .             .   *  V  ''  .  ^  ,  '^       6S 

Crystalline,                .           ;,  »  .  >v. "'."       18 

Crystalline  limestone,           .  •-  *"'.'  •»          96 

Cuvier,          .             .             .  .  .  .ir       252 

D. 

Day,  interpretation  of,      ,     •  •  31,38 

De  La  Beche,           .             .  .  ^  .        25Q 

De  La  Heche's  classification  of  rocks,  .  8b 

Delta,                        .  ll* 

DeLuc,                    .             .  ;"  .  .        2&1? 

De  Maillet,              ...  .24? 


INDEX.  271 

Density,  mean  of  the  earth,  ...          18 

Diamond,  .....  52 

Diluvion,  .  ^  .  .87 

"         description  of,          .  .  .  .135 

"         distinguished  from  alluvion,  .  136,  150 

Dip, 75 

"     calculation  of,  ....  78 

"     line  of,  ....  75 

"     apparent,  apt  to  be  mistaken  for  the  true, 

Dislocation  of  strata,  .  .  .  82,  165 

Disseminated,  .  .  .  .  .17 

Douglass,  .....         249 

Drainage  of  soils,  .  .          215, 219, 222, 225 

Drowning,  .....  50 

Dyke,  ....  82,  170 

"     definition  of  and  description,  .  .         164 

Dykes  of  Carolina,  .  .  .  .166 

"      on  the  banks  of  rivers,  .  '.  .         155 

"      of  trap,  .  .  .  .  .164 

"          "      effects  of  on  rocks,  .  .        166 

E. 

Earth,  what  made  of,           .           >;          .  .          15 

Earthquakes,  .  .  .  .  .172 

"  Antioch  destroyed  by,  .  .  176 

"  of  Caraccas,  .  .  .  177 

"  causes  of,  .  .  .  JL77 

"  coast  of  Chili  raised  by,  .  .  176 

"  Euphemia  destroyed  by,  .  .  173 

"  extent  of  effects,  .  .  .174 

"  frequent  at  particular  times  .  175 

"  of  Lisbon,  .  .  174,176 

"  of  the  Mississippi,  .  .  .  177 

'*  most  common  in  volcanic  districts,  172,  175 

"  oscillations  of  the  ground,  .  .  178 

"  Temple  of  Serapis  sunk  and  raised,  1,77 

Earths,  .....  53 

"  alkaline,  .  .  .  .  .53 

Earthy  fracture,        .                        .            .  .71 


272 


INDEX. 


East  Rock  of  New  Haven, 

Eaton,  Professor, 

Ebel, 

Ecliptic,  obliquity  of, 

Elastic  bodies, 

Electrified  bodies, 

Elementary  bodies, 

Elevation  of  continents, 

Elevated  beds, 

Elie  de  Beaumont, 

Encrinites, 

Encrinal  limestone, 

E peris,  salt  mine  of, 

Epochs, 

Erratic  blocks, 

Eurite,  .        I* 


F. 


Fault,  '" .  V : 

Feldspar,  .        /    »,, 

"        description  of> 
"         compact,  * 

Ferns,  impressions  of,  .  , 

Firestone, 
Fissile, 
Flint, 

"     composition  of,  • 

Fluorine, 

Fluoric  acid,  »    i 

Fluor  spar,  '....«'.         •    - 

Forest,  petrified, 
Formations,          I     •  • 

Fossil  birds,  .  A          •  & 

"     fish, 
Fossils  abound  in  some  rocks, 

"      at  great  depths,  . 

«•      defined,       '     . 

"      different  genera  in  different  rocks, 

"      monuments  of  changes, 


INDEX.  273 

Fossils  of  salt  licks,  .  .  .  ^        119 

Fracastero,  ...  .         246 

Fracture,  .....  71 

Free  atones,  .  .  .  .  .105 

Fox,  252 

Fuchsell,  .....        249 

G. 

Ganges,         .....  151,  155 

Garnet,         ......  95 

"      in  volcanic  rocks,  .  .  .192 

Gaseous,  .....  50 

Geography,  .  .  .  .  .13 

Geologists,  European,  •  '•'.'-:        .  .  .         252 

French,  ....         252 

«          German,  .  252 

"          American,  ....         252 

Geology,  .  .  .  .  14,  31 

"         agrees  with  the  Mosaic  account,  .  31 

"         consistency  of  with  the  Bible,          .  33,  38 

"         foundation  of,        s  .  .  .  .  25 

"         history  of,  .  .  .  .        244 

Geological  alphabet,  .  ,'          .  16,62 

"         equivalents,        ,  .  *        »  .  85 

maps,  v  219,  224,  230, 234, 249 

Geysers,  .';. .'       •.     ,.-.          »  •  .         182 

Glass,       ;*  V  .  «  »  .  .          52 

Glacier,  fall  of,          .  ,  .  .  152,  153 

Glucinum,  -    •  »  •  *-*•          •  58 

Gneiss  rock,  ^  . .  '        ,   -.       , «  .  93,  94 

Gneissoid,  hornblende,          •  ^        •  .  .  94 

Gold,  .  V  .  .  .  60 

Granite,  .          <  ..-      ,    •+      ^  ^  .          90 

"         porphyritic,  ,         *    »  .  .  91 

«*         graphic,  ....  93 

«•         protogine,  .  .  .  .          91 

"         sienitic,        .....  91 

««         veins,  .  .  ...  .92 

Granular  structure,          ,     »  .  .  .          17 


274 


INDEX. 


Greenough, 
Greenstone, 
Graywacke, 


Grindstones, 
Ground,  swell, 
Guettard, 
Gypsum  described, 


H. 


Hall's  experiment  on  basalt, 

"  limestone, 

Hayden,        .  .  •    . 

Heat,  .        ;    .J    fe... 

Herculaneum,       .    »'/'' 
Herschell's  views  of  geology, 
Himmalaya  mountains, 
Hitchcock,  ..  •;• 

Hollo  way, 

Hooke,  -.;, 

Hornblende,          ;  ;.+     .     • 
"  rock,  '• 

"  slate,  . 

Hornstone,  !•  -  4  •  *• 

Human  bones,  .  * 

Hutton,  |  •'•*'.-"'.         •• 

Huttonian  theory,  s     • 

Hydraulic  cement,  * 

Hydrogen,  .          r  >' 


I. 


Icebergs,  ,;.        ^  . 

Iguanodon,  .          -  • 

Inclined  strata, 
Independent  coal  formation, 
Inferior  rocks,  .         .     • 

Insects  imbedded  in  amber, 
Iodine,          .  .'  'f* 


INDEX. 


275 


Iridium, 
Iron,  cast, 


ores, 

"  in  volcanic  rocks, 
generally  diffused 
pyrites, 


James,  Dr., 

Jasper, 

Jet,  a  kind  of  wood  coal, 

Jorullo,  volcano  of, 


Kaolin,  or  porcelain  clay, 
Kefferstein, 


J. 


K. 


L. 


Lake  Huron, 

retreat  of, 
Laminar, 
Lava, 

"     quantities  erupted, 
Lead, 

"    ores, 
Lehman, 
Lias  limestone, 

"     clay, 

Light,  evidence  of,  in  ancient  times  of  the  earth, 
Lignite,  a  kind  of  wood  coal, 
Lime,  its  uses  on  soils, 
Limestone  described,  ^ 

"        encrinal, 
"        how  distinguished, 
••        magnesian, 
**        metalliferous, 
"        mountain, 


61 

52 

53,  105 

192 
53 

192 


25S 

52 

113 

176 


93 
252 


27 

27 

64 
183 
184 

59 

17,  102 

25,  249 

121 

121 

44 

112,  113 
227 

69 
102 

70 
115 
102 
108 


276  INDEX. 

Limestone  transition,             .             .  .  .101 

'*         caves  in,               .             .  .  .103 

"         springs  in,             .             .  .  .103 

Liquidity  of  earth,                 ....  18 

Llwydd,  248 

Lister,  .....         248 

Lithium,                    .             .         '  ^  .  v  .  .           57 

Lithography,             .            &       .  •'•'"•  ;  ,    ';•        121 

London  chalk  basin,           •  ,A             .  •* ,  .   '      132 

Lunar  irregularities          .»»•'./        •  •'*.-'-.  •. •..,'•  •< •••      20 

M. 

Maclure,  American  geologist,      •,     . '  M  *  .        253 

Madrepores,               .             .             .  ^  •  .  .         124 

Magnesia,  composition  of,                 ,  -  V  •  ';,  ;;l      49 

'*         injurious  to  vegetation,  .  .         115 

Magnesian  limestone,            .             .  .  .115 

Magnesium.                                          •  .  .           49 

Man,  latest  tenant  of  globe,              .  •    ••  ~\    "      32 

Manganese,                .         v   .             .  .  .    '       58 

Maps,  geological,  . .          219,  224,  230,  234,  249 

Marbles,                      .  .          ,  ,-         f,,  ,,  **"  *   "      70 

"         white,         .             .  t          .  ' .'  :.St^.      96 

"         variegated,         •    *  „     "'  »  ,  •  •         104 

"         verd  antique,          .             .  .  *,         71 

"                "            of  New  Haven,  .\  ;          96 

Marine  and  fresh  water  remains,  .  .         132 

Marl,             .            .            .            .'  ,  70,227 

Massive,                     •.          **      ».«.  .  63,67 

Mastodon,                  .,      .   V ,          »  ,'  .  '•         119 

"         extinct,                  .             .  .  .119 

McCulloch,           ,  ^  ,          .^        .  ,«,  •        252 

Mean  density  of  the  earth,                .  ,  F   ,-.  •. 

Medial  rocks,                     ? ;  >  (          .  :«.  ,.  •  - 

Megalosaurus,                        «,          *  -•'•-.(.  •        ^27 

Mercury,                     . «          •  -^        •  t ;  •           ^ 

Metals,                       .        ;-.'.          .  :^;v  l*,* 

'«        earthy  and  alkaline,             .  .  . .       206 

Metalliferous  limestone,          .      .    •  &  •  **-      ^^ 


INDEX. 


277 


Mica,  description  of, 

"     slate, 
Millepores, 
Mineral,  definition  of, 
Minerals  associated, 

"      composed  of, 

"      number  of, 
Mining, 
Mississippi,  . 

"         delta  of, 

"         earthquakes  of, 
Mitchell, 

Molybdenum  .  . 

Monte  Bolca,  .^ 

Morton,  Dr.,  American  geologist, 
Mosaic  account  of  the  creation, 
Mountain  limestone, 
Mount  Holyoke, 
Moving  power  of  water, 
Moya, 

Murchinson,  ,•*" .       ^P 

Muscovy  glass  or  mica,     ..  ,* 


Newcastle  coal  mines, 

New  Haven  marble, 

Nickel, 

Nitrogen,  , 


Objects  of  geology, 
Ocean,  mean  depth  of, 


N. 


O. 


and  land  have  chang  d  their 


Oil  contains  carbon, 

"  of  vitriol, 
Olivine, 
Olmsted, 
Oolitic  rocks, 


relative  levels, 


64 

94 

124 

16 

17 

48 

48 

238 

151,  155 

151,  155 

177 

249 

57 

134 

127,  252 

31 

101 

164 

156 

181 

252 

65 


109 
96 
58 

•55 


15 
51 

26 
52 

49,53 
192 
252 
123 


24 


278 


INDEX. 


Oolitic  rocks,  organic  remains  of, 
Opake,  definition  of, 
Ores  of  copper  and  lead, 

iron, 

clay  iron  stone, 

in  transition  rocks, 

of  lead  and  silver, 

in  volcanic  rocks, 
Organic  remains  defined, 
Osmium,  .  »', 

Outcrop  of  strata,  ' , , 

Ovid,  .*, 

Owen,  .         Hf  • ., 

Oxides,  definition  of,  * , 

Oxygen,  >  *•?,        » . 

P. 

Packe, 

Palisades  of  the  Hudson, 

Pallas, 

Parkinson,  <,;"' 

Paris  chalk  basin, 

Peat  bogs, 

"        origin  of, 

"        uses  and  qualities 

Petrifactions, 

Petrified  forest, 

Phenomena,  indicating  cent  al  heat 

Phillips, 

Phosphorus,  . 

Pitchstone,  . 

Platinum,  » 

Pliny,  _>• 

Plumbago, 

Polygon, 

Pompeii,  destruction  of, 

Porcelain  clay,         *    .   : 

Porphyritic  structure, 

Porphyry, 


INDEX. 


279 


Porphyry  of  Andes  and  Cordilleras,  .  164,  192 

Potassa,  composition  of,  ...          49 

Potassium,  .....  49 

Primitive  forms  of  crystals,  ...  69 

"  limestone,  ...  96 

"  rocks,  .  .  26,  89 

Prism,  .  .  .  .  .169 

Protogine,  .  .  .  .  .91 

Padding  stone,          .....         100 
Pumice,  .....         193 

Pussey,  Professor,  on  interpretation,  .  .  42 

Q. 

Quartz,  composition  of,  .            .  52,  62 

"       constituents  of  rocks,  ...  63 

"       description  of,  ...  62 

"       rock,                          .  .  97 

R. 

Radiant  heat  of  earth,          ....  20 

Rag  coral,  .....         124 

Rapidity  of  motion  in  earthquakes,  .  .          20 

Raumer,  .....        253 

Ray,  .  ;    .  /         .  .         248 

Recapitulation  of  geological  facts,  .  .         194 

Red  marl,  \    .  .  .  .115 

"        sandstone,  .  .  .  100,  115 

new,  .  .  100,  115 

old,  ..  -•         .  .        100 

Reeds,  impressions  of  in  shale,        «  .  .110 

Refraction,  .  .        '     «   .          .  .  69 

"         double,  ££        V  .  .70 

Rhodium,  .  ...  .  .  .  61 

Rhomboid,  .  ,  ...  69 

Rivers  engulphed,  ....         103 

"       elevate  their  beds  in  some  places,  .         155 

Roads,  expense  of  construction,  .  .        229 

"      cuttings  of,  .  .  .  230,232 


'280 


INDEX. 


Roads,  drainage  of,  ....        230 

durability  of,  ....        232 

macadamized,  ....        230 

materials  for,  •  231 

planned,  .*!  .  .  .  .  230 

stoning  of,  *.' . . '  .  .  .  230 

in  stratified  rocks,  jfl  ^*V  .  230 

Rock  crystal,  .  '*"'  V  '  •  '  •  «•  *  '  52 

"  salt,  .  '  v  *>£;:  116,118,120 

Rocks,  definition  of,  .  .  t,  .  16,17 

"  have  the  same  relative  situations,  ,  .  .  /  72 

Roe  stone,  or  oolite,              .  .            .            .         123 

Roof  slate,                  .           V ' . J  .' "      .   *        !  „           98 

s. 

Safety  lamp,              .             .  V       L*             •         178 

Salammoniac,  a  volcanic  product,  ••,.».'         •         193 

Salt,  composition  of,  .                       51 

in  the  ocean,                 .    <i  .            ,          51 

lakes,                .             .  .            .        117 

licks,                 .             .  >.  ,         ..       119 

"     big  bone  lickj  .            .        119 

mines,                .           .^,,  .,,            •,*-,,         117,118 

reservoir  of,      .            •'  '         '  •'"'         ";         121 

rock,             ' "•''»             .  .              116,118 

springs,             .            ;?.  ,  ,  ..  _ •_,        %            .         118 

"        origin  of,       ,'^  tr-;'J          .        119 

Sand,  composition  of,            «  *.           .          52 

"     drifting  of,  .                          .         157 

Sandstone,                  .             .  *^       100,  105,  115,  128 

"        old  red,                 .  100 

"         new  red,                .  "**  H          .             .         115 

Saurian  animals,                    .  116,  122,  125,  127 

Saussure,                   .           -.  .                      .         252 

Screw  stones,  or  encrinites,  .             .         102 

Secondary  rocks,                     .  ( +       ,  ' .           26 

"           described,  ,:              >s'        •         104 

Sedgwick,  Professor,             .  V-V            •        252 

Selenium,                  .            *^  '  *    "        ,    '      56 


. NDEX.  281 

Serpentine  described,  .  .  .  .71 

«         rock,  ...  96 

*         with  limestone,  forms  a  rare  and  valuable 

marble,  .  .  .  71,  96 

Shale,  .  ....         105 

"     distinguished  from  slate,          ...  98 

"     bituminous,  ....         135 

"     contains  impressions  of  plants  .  .         105 

fish,  .  .        135 

Shells  of  the  tertiary,  .  .  .     131,  132,  133 

Shoals, 159 

Sienite,  91 

Sienitic  greenstone,  .  .  .  .164 

Silex,  or  silica,  .  .  ,  48,  52 

Silicon,  .....  52 

Silliman,  Professor,  .  .  .  206,  252 

Silver,  .  ...  .  .60 

Simple  or  elementary  bodies,  .  - .  48,  54 

Sink  holes  in  limestone,         ....         103 

Skapta  Jokul,  of  Iceland,  .  .  184,  188 

"  lava  currents  of,         .  .  .184 

Tjlate,  description  of,  ...  71,  98 

"      alum,  .  .  .  .123 

"      argillaceous,  ....          98 

*4      clay,  or  shale,         "••'..         .  •  •         105 

"      composition  of,  »  •  •  .71 

"      graywacke,  ',  .  .  .  99 

"     roof,  >  *.  .  .  .          99 

"     stratification  of,          ....  .          99 

Slaty  structure,  .  .  .  .     '      18 

Smith,  William,  English  geologist,  .  .        252 

Soda  and  sodium,  ....          49 

Soils,  alluvial,          V"         *        ;    «~         •  •        223 

"     argillaceous,  t  V  .  .         214 

"     composition  of,  .'  .  .  214,  226 

"     drainage  of,  #    ;         .  215,  219, 222 

"     formation  of,  ....        213 

"    improvement  of,          .  .  215, 220,  226 

"    light,  .  .  .  .216 

••    permanency  of,  .  .  .  .217 

24* 


282 


INDEX. 


Soils,  stimulants  for,  .             .  .             .216 

"     substratum  of,  ...  215,  220 

"     texture  of,  .             .  .             214,218 

"     varieties  of,  .             .  .             .214 

Specific  gravity,  • .           •  •        «  ' .  18 

Sponges,  fossil,  :  '«»  ?        •  •             •  124 

Spongiform,               .        >.   „        .vV"'  .  .  63 

Springs,  boiling,  of  Iceland,  .  .             .  182 

"              "          of  Arkansas,         .  &    .  ,  *  182 

"         and  streams  from  limestone,  .        <    .  103 

Stalactical,                .  •»'-..  .        ,     ,  ^  63 

Stalactites,                 .  .'       %/  .  V.             .  148 

Staurotide  in  mica  slate,  '.  .             .  95 

Steel,  composition  of,  f            .  ,             .  52 

Strabo,        ''\  ;.'  ,  '  >  '  *     .  244 

Strachey,       .  ;  .     .  .  248 

Strata,                       .  .         .;;v  .                26,  27 

"    not  always  level,  .            .  ,        <!  *V  73 

Stratification,  ....  72 

"            conformable,  ...  76 

"            unconformable,  •  • ,          .    *;  76 

"             contorted,  .  .          .^  %  77 

"             of  slate,  '                .  .             .  76 

"            of  gneiss,  •  ,;,?*,,     k'I'* ;  -  94 

Strontium,                 ,  '  „  ..;*'•        .  58 

Structure,  columnar,  .  162,  166,  169 

"         compact,  ...  17 

"        crystalline,  .  ,         ;'•*-•'  18 

"         granular,  .  .        '  i;»  -  18 

"        porphyritic,  .  »y^        »-i«  91 

"         slaty,  .  v;.;Yv     f\w  t  18 

St.  Vincens,  eruption  of,  *  '  '  t» '••,'      .  •  177 

Sulphur,                    .  .  .        •:,-i«if«r  53 

"        in  volcanos,  «  .»«?••<•,     ;  *  193 

Sulphuric  acid,  .  •  ';.        *  49 

Sulphurous  acid,  .  >  -  *t  &;v  ;*?-:>.  49 

Sumbawa,  eruption  in,  .  \*  ,      v    » .  184 

Superior  rocks,  .  !.,*..  »^gj?  88 

Supermedial  rocks,  ...  88 

Swallow  holes,  «•>•  w  w,;          •  103 


INDEX.  283 

T. 

Talc  described,           .  .          67 

Talcose  slate,             .  .          95 

"         granite,  .           91 

Taylor,                       .  .        252 

Tellurium,                  .  .           57 

Temperature  of  the  earth  .           19 

"         of  interior  of  the  earth  explained,  21 

"         increases  with  the  depth,  .          21 

"        variable  near  the  surface,  .          21 

Teneriffe,  peak  of,                  .             .  .        191 

Tertiary  rocks,           .             ,  86,  128 

confounded  with  alluvial,  .         129 

rarely  intersected  by  dykes,  .        132 

fossils,  mammalia,                .  .    "    130 

fossil  shells,             ...  .131 

fossil  birds,  fish,  and  animals,  130,  134 

Testaceous  animals,                           .  .102 


Thales, 

Theories,  geological, 


Huttonian  theory 
"        Wernerian  theory 
Thorium, 

Tides  of  the  Amazon, 
Nova  Scotia, 


244 
199 

199,  203 

199,  200 

58 

140 

141 


"       the  bay  of  Fundy,  .  .         141 

"       transporting  power  of,  .        ,156 

Time  required  to  produce  changes  on  the  ear  h's  surface,     30 

Tin  ores,                    .             .  .  17,59,93 

Titanium,                  ...  .57 

Topaz  associated  with  tin,  .  ,17 

Torrents,                   *             .  .  150,  156 

Trachyte,                 .'.            .  «  ~  142,  193 

Transition  rocks,                   ,  .  86,  97 

"  "     metalliferous,  * 

"        limestone, 
Trap  rocks  described, 

"        composition  of,  .  95,  162 

•*        experiments  on,  .  •        167 


284 


INDEX. 


Trilobites,  eyes  of, 
Tropical  fossils, 
Tuchsel, 
Tungsten, 


u. 


Unconformable  rocks,       '.* .,  , 
"  stratifications, 

Upper  secondary  rocks, 
Uranium,  :*'  •         «*i  ..u  > 

V. 

Valleys,  .^ 

44      of  denudation, 
Vanadium, 
Van  Renseelaer, 
Variegated  sandstone, 
Veins, 

"    metallic,         .V 
"    walls,  floor  and  roof  of, 
Velocity  of  rotation  of  earth 
Verd  antique  marble, 

"  of  New  Haven, 

Volcanic  islands,  formation  of, 

"  often  sink, 

"      rocks, 

"        "    constituents  of, 
"      mountains,  conical, 
"      mountains  sometimes  engulfed, 
Volcano,  ^Etna,        . 
Jorullo, 
Papandayang, 
Peak  of  Teneriffe, 
Pic, 

Skapta  Jokul, 
Sumbawa, 
Vesuvius, 
[  description  of, 


45 

19 

249 

57 


162 
76 

114 
57 


27 

29,81 
57 
253 
115 
86 
247 
17,86 
19 
71 
96 
188,  189 
188,  189 
162,  181, 192 
192 
180 
190 

176,  183 
176 
190 
190 
190 

184;  188 
184 

181, 185 
179 


INDEX. 


285 


Volcanos,  fish  from, 

floods  of  ashes  from, 
long  repose  of, 
often  in  groups, 
submarine, 
simultaneous  action  of, 


Voltaire 


w. 


Wacke,          . 

Warmth  variable  below  the  surface, 

Water,  boring  for, 

"      composition  of,  .  , 

Watt,  Gregory,  experiments  of, 
Waves,  power  of,  .  . 

Webster,  English  geologist,  , 

"       American  geologist, 
Welielska  salt  mine,  .  . 

Wells  ..... 
Werner,  , 

Werner  and  Hutton  compared, 
Wernerian  theory,  . 

West  rock  of  New  Haven,  « 

Wheel  whirls,  .«  .    .         , 

Whetstones,  *  *  , 

Whetstone  slate,  ,  , 

Whiston,  ,  4'  4 

Whitehurst,  f 

Wind,  action  of  in  transport,  < 

Wood  contains  carbon,          .  , 

14      coal,  .  *          .  , 

Woodward,  «  »..';          , 


Y. 


Yellow-stone  river, 
Youth,  influence  of, 
Yttrium,  , 


180 
180 
187 
190 
188 
21 
246 


163 

21 
133 

49 
168 
142 
252 
252 
117 
236 
250 
254 
200 
163 
102 
105 

99 
248 
249 
157 

52 
113 
248 


158 

255 

58 


286  INDEX. 

Z. 

Zeno,            .            .            ..'.A.  .        244 

Zinc,             ,            .                    .  .. /•  59 

"    ores,                •            •            •            .  .          17 

Zirconium,                •            .        *.  ^  J/       ^  5g 


YA   Q£2£ 

U.  C.  BERKELEY  LIBRARIES 


M' 
Sir 


THE  UNIVERSITY  OF  CAUFORNIA  LIBRARY 


